diff --git a/src/storm-parsers/parser/JaniParser.cpp b/src/storm-parsers/parser/JaniParser.cpp
index f3105d6ca..a5cc1c792 100644
--- a/src/storm-parsers/parser/JaniParser.cpp
+++ b/src/storm-parsers/parser/JaniParser.cpp
@@ -301,15 +301,11 @@ namespace storm {
                     assert(bound == boost::none);
                     STORM_LOG_THROW(false, storm::exceptions::NotImplementedException, "Forall and Exists are currently not supported");
                 } else if (opString == "Emin" || opString == "Emax") {
-                    bool time=false;
                     STORM_LOG_THROW(propertyStructure.count("exp") == 1, storm::exceptions::InvalidJaniException, "Expecting reward-expression for operator " << opString << " in  " << scope.description);
                     storm::expressions::Expression rewExpr = parseExpression(propertyStructure.at("exp"), scope.refine("Reward expression"));
-                    if (rewExpr.isVariable()) {
-                        time = false;
-                    } else {
-                        time = true;
-                    }
-
+                    STORM_LOG_THROW(rewExpr.hasNumericalType(), storm::exceptions::InvalidJaniException, "Reward expression '" << rewExpr << "' does not have numerical type in " << scope.description);
+                    std::string rewardName = rewExpr.toString();
+ 
                     storm::logic::OperatorInformation opInfo;
                     opInfo.optimalityType =  opString == "Emin" ? storm::solver::OptimizationDirection::Minimize : storm::solver::OptimizationDirection::Maximize;
                     opInfo.bound = bound;
@@ -319,64 +315,43 @@ namespace storm {
                         rewardAccumulation = parseRewardAccumulation(propertyStructure.at("accumulate"), scope.description);
                     }
                     
+                    bool time = false;
                     if (propertyStructure.count("step-instant") > 0) {
                         STORM_LOG_THROW(propertyStructure.count("time-instant") == 0, storm::exceptions::NotSupportedException, "Storm does not support to have a step-instant and a time-instant in " + scope.description);
                         STORM_LOG_THROW(propertyStructure.count("reward-instants") == 0, storm::exceptions::NotSupportedException, "Storm does not support to have a step-instant and a reward-instant in " + scope.description);
 
                         storm::expressions::Expression stepInstantExpr = parseExpression(propertyStructure.at("step-instant"), scope.refine("Step instant"));
                         if(rewardAccumulation.isEmpty()) {
-                            if (rewExpr.isVariable()) {
-                                std::string rewardName = rewExpr.getVariables().begin()->getName();
-                                return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::InstantaneousRewardFormula>(stepInstantExpr, storm::logic::TimeBoundType::Steps), rewardName, opInfo);
-                            } else {
-                                STORM_LOG_THROW(false, storm::exceptions::NotSupportedException, "Only simple reward expressions are currently supported");
-                            }
+                             return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::InstantaneousRewardFormula>(stepInstantExpr, storm::logic::TimeBoundType::Steps), rewardName, opInfo);
                         } else {
-                            if (rewExpr.isVariable()) {
-                                std::string rewardName = rewExpr.getVariables().begin()->getName();
-                                return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::CumulativeRewardFormula>(storm::logic::TimeBound(false, stepInstantExpr), storm::logic::TimeBoundReference(storm::logic::TimeBoundType::Steps), rewardAccumulation), rewardName, opInfo);
-                            } else {
-                                STORM_LOG_THROW(false, storm::exceptions::NotSupportedException, "Only simple reward expressions are currently supported");
-                            }
+                            return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::CumulativeRewardFormula>(storm::logic::TimeBound(false, stepInstantExpr), storm::logic::TimeBoundReference(storm::logic::TimeBoundType::Steps), rewardAccumulation), rewardName, opInfo);
                         }
                     } else if (propertyStructure.count("time-instant") > 0) {
                         STORM_LOG_THROW(propertyStructure.count("reward-instants") == 0, storm::exceptions::NotSupportedException, "Storm does not support to have a time-instant and a reward-instant in " + scope.description);
-
                         storm::expressions::Expression timeInstantExpr = parseExpression(propertyStructure.at("time-instant"), scope.refine("time instant"));
-
                         if(rewardAccumulation.isEmpty()) {
-                            if (rewExpr.isVariable()) {
-                                std::string rewardName = rewExpr.getVariables().begin()->getName();
-                                return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::InstantaneousRewardFormula>(timeInstantExpr, storm::logic::TimeBoundType::Time), rewardName, opInfo);
-                            } else {
-                                STORM_LOG_THROW(false, storm::exceptions::NotSupportedException, "Only simple reward expressions are currently supported");
-                            }
+                            return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::InstantaneousRewardFormula>(timeInstantExpr, storm::logic::TimeBoundType::Time), rewardName, opInfo);
                         } else {
-                            if (rewExpr.isVariable()) {
-                                std::string rewardName = rewExpr.getVariables().begin()->getName();
-                                return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::CumulativeRewardFormula>(storm::logic::TimeBound(false, timeInstantExpr), storm::logic::TimeBoundReference(storm::logic::TimeBoundType::Time), rewardAccumulation), rewardName, opInfo);
-                            } else {
-                                STORM_LOG_THROW(false, storm::exceptions::NotSupportedException, "Only simple reward expressions are currently supported");
-                            }
+                            return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::CumulativeRewardFormula>(storm::logic::TimeBound(false, timeInstantExpr), storm::logic::TimeBoundReference(storm::logic::TimeBoundType::Time), rewardAccumulation), rewardName, opInfo);
                         }
                     } else if (propertyStructure.count("reward-instants") > 0) {
                         std::vector<storm::logic::TimeBound> bounds;
                         std::vector<storm::logic::TimeBoundReference> boundReferences;
                         for (auto const& rewInst : propertyStructure.at("reward-instants")) {
-                            storm::expressions::Expression rewInstExpression = parseExpression(rewInst.at("exp"), scope.refine("Reward expression"));
-                            STORM_LOG_THROW(!rewInstExpression.isVariable(), storm::exceptions::NotSupportedException, "Reward bounded cumulative reward formulas should only argue over reward expressions.");
+                            storm::expressions::Expression rewInstRewardModelExpression = parseExpression(rewInst.at("exp"), scope.refine("Reward expression at reward instant"));
+                            STORM_LOG_THROW(rewInstRewardModelExpression.hasNumericalType(), storm::exceptions::InvalidJaniException, "Reward expression '" << rewInstRewardModelExpression << "' does not have numerical type in " << scope.description);
+                            std::string rewInstRewardModelName = rewInstRewardModelExpression.toString();
+                            if (!rewInstRewardModelExpression.isVariable()) {
+                                nonTrivialRewardModelExpressions.emplace(rewInstRewardModelName, rewInstRewardModelExpression);
+                            }
                             storm::logic::RewardAccumulation boundRewardAccumulation = parseRewardAccumulation(rewInst.at("accumulate"), scope.description);
-                            boundReferences.emplace_back(rewInstExpression.getVariables().begin()->getName(), boundRewardAccumulation);
+                            boundReferences.emplace_back(rewInstRewardModelName, boundRewardAccumulation);
                             storm::expressions::Expression rewInstantExpr = parseExpression(rewInst.at("instant"), scope.refine("reward instant"));
                             bounds.emplace_back(false, rewInstantExpr);
                         }
-                        if (rewExpr.isVariable()) {
-                            std::string rewardName = rewExpr.getVariables().begin()->getName();
-                            return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::CumulativeRewardFormula>(bounds, boundReferences, rewardAccumulation), rewardName, opInfo);
-                        } else {
-                            STORM_LOG_THROW(false, storm::exceptions::NotSupportedException, "Only simple reward expressions are currently supported");
-                        }
+                        return std::make_shared<storm::logic::RewardOperatorFormula>(std::make_shared<storm::logic::CumulativeRewardFormula>(bounds, boundReferences, rewardAccumulation), rewardName, opInfo);
                     } else {
+                        time = !rewExpr.containsVariables() && storm::utility::isOne(rewExpr.evaluateAsRational());
                         std::shared_ptr<storm::logic::Formula const> subformula;
                         if (propertyStructure.count("reach") > 0) {
                             auto formulaContext = time ? storm::logic::FormulaContext::Time : storm::logic::FormulaContext::Reward;
@@ -384,34 +359,16 @@ namespace storm {
                         } else {
                             subformula = std::make_shared<storm::logic::TotalRewardFormula>(rewardAccumulation);
                         }
-                        if (rewExpr.isVariable()) {
-                            assert(!time);
-                            std::string rewardName = rewExpr.getVariables().begin()->getName();
-                            return std::make_shared<storm::logic::RewardOperatorFormula>(subformula, rewardName, opInfo);
-                        } else if (!rewExpr.containsVariables()) {
-                            assert(time);
+                        if (time) {
                             assert(subformula->isTotalRewardFormula() || subformula->isTimePathFormula());
-                            if(rewExpr.hasIntegerType()) {
-                                if (rewExpr.evaluateAsInt() == 1) {
-                                    return std::make_shared<storm::logic::TimeOperatorFormula>(subformula, opInfo);
-                                } else {
-                                    STORM_LOG_THROW(false, storm::exceptions::NotSupportedException, "Expected steps/time only works with constant one.");
-                                }
-                            } else if (rewExpr.hasRationalType()){
-                                if (rewExpr.evaluateAsDouble() == 1.0) {
-                                    
-                                    return std::make_shared<storm::logic::TimeOperatorFormula>(subformula, opInfo);
-                                } else {
-                                    STORM_LOG_THROW(false, storm::exceptions::NotSupportedException, "Expected steps/time only works with constant one.");
-                                }
-                            } else {
-                                STORM_LOG_THROW(false, storm::exceptions::InvalidJaniException, "Only numerical reward expressions are allowed");
-                            }
-                            
+                            return std::make_shared<storm::logic::TimeOperatorFormula>(subformula, opInfo);
                         } else {
-                            STORM_LOG_THROW(false, storm::exceptions::NotSupportedException, "No complex reward expressions are supported at the moment");
+                            return std::make_shared<storm::logic::RewardOperatorFormula>(subformula, rewardName, opInfo);
                         }
                     }
+                    if (!time && !rewExpr.isVariable()) {
+                        nonTrivialRewardModelExpressions.emplace(rewardName, rewExpr);
+                    }
                 } else if (opString == "Smin" || opString == "Smax") {
                     STORM_LOG_THROW(false, storm::exceptions::NotImplementedException, "Smin and Smax are currently not supported");
                 } else if (opString == "U" || opString == "F") {
@@ -462,12 +419,14 @@ namespace storm {
                         for (auto const& rbStructure : propertyStructure.at("reward-bounds")) {
                             storm::jani::PropertyInterval pi = parsePropertyInterval(rbStructure.at("bounds"), scope.refine("reward-bounded until").clearVariables());
                             STORM_LOG_THROW(rbStructure.count("exp") == 1, storm::exceptions::InvalidJaniException, "Expecting reward-expression for operator " << opString << " in  " << scope.description);
-                            storm::expressions::Expression rewExpr = parseExpression(rbStructure.at("exp"), scope.refine("Reward expression"));
-                            STORM_LOG_THROW(rewExpr.isVariable(), storm::exceptions::NotSupportedException, "Storm currently does not support complex reward expressions.");
+                            storm::expressions::Expression rewInstRewardModelExpression = parseExpression(rbStructure.at("exp"), scope.refine("Reward expression at reward-bounds"));
+                            STORM_LOG_THROW(rewInstRewardModelExpression.hasNumericalType(), storm::exceptions::InvalidJaniException, "Reward expression '" << rewInstRewardModelExpression << "' does not have numerical type in " << scope.description);
+                            std::string rewInstRewardModelName = rewInstRewardModelExpression.toString();
+                            if (!rewInstRewardModelExpression.isVariable()) {
+                                nonTrivialRewardModelExpressions.emplace(rewInstRewardModelName, rewInstRewardModelExpression);
+                            }
                             storm::logic::RewardAccumulation boundRewardAccumulation = parseRewardAccumulation(rbStructure.at("accumulate"), scope.description);
-                            tbReferences.emplace_back(rewExpr.getVariables().begin()->getName(), boundRewardAccumulation);
-                            std::string rewardName = rewExpr.getVariables().begin()->getName();
-                            STORM_LOG_WARN("Reward-type (steps, time) is deduced from model type.");
+                            tbReferences.emplace_back(rewInstRewardModelName, boundRewardAccumulation);
                             if (pi.hasLowerBound()) {
                                 lowerBounds.push_back(storm::logic::TimeBound(pi.lowerBoundStrict, pi.lowerBound));
                             } else {
@@ -478,7 +437,6 @@ namespace storm {
                             } else {
                                 upperBounds.push_back(boost::none);
                             }
-                            tbReferences.push_back(storm::logic::TimeBoundReference(rewardName));
                         }
                     }
                     if (!tbReferences.empty()) {
diff --git a/src/storm-parsers/parser/JaniParser.h b/src/storm-parsers/parser/JaniParser.h
index 304715801..4e7489b32 100644
--- a/src/storm-parsers/parser/JaniParser.h
+++ b/src/storm-parsers/parser/JaniParser.h
@@ -122,6 +122,7 @@ namespace storm {
             std::shared_ptr<storm::expressions::ExpressionManager> expressionManager;
             
             std::set<std::string> labels = {};
+            std::unordered_map<std::string, storm::expressions::Expression> nonTrivialRewardModelExpressions;
 
             bool allowRecursion = true;
 
diff --git a/src/storm/storage/jani/ArrayEliminator.cpp b/src/storm/storage/jani/ArrayEliminator.cpp
index e39a5d7e3..9bedb334a 100644
--- a/src/storm/storage/jani/ArrayEliminator.cpp
+++ b/src/storm/storage/jani/ArrayEliminator.cpp
@@ -445,6 +445,9 @@ namespace storm {
                     if (model.hasInitialStatesRestriction()) {
                         model.setInitialStatesRestriction(arrayExprEliminator->eliminate(model.getInitialStatesRestriction()));
                     }
+                    for (auto& nonTrivRew : model.getNonTrivialRewardExpressions()) {
+                        nonTrivRew.second = arrayExprEliminator->eliminate(nonTrivRew.second);
+                    }
                 }
                 
                 virtual void traverse(Automaton& automaton, boost::any const& data) override {
diff --git a/src/storm/storage/jani/FunctionEliminator.cpp b/src/storm/storage/jani/FunctionEliminator.cpp
index 152dfc77f..fcdaa0b34 100644
--- a/src/storm/storage/jani/FunctionEliminator.cpp
+++ b/src/storm/storage/jani/FunctionEliminator.cpp
@@ -284,6 +284,9 @@ namespace storm {
                     if (model.hasInitialStatesRestriction()) {
                         model.setInitialStatesRestriction(globalFunctionEliminationVisitor.eliminate(model.getInitialStatesRestriction()));
                     }
+                    for (auto& nonTrivRew : model.getNonTrivialRewardExpressions()) {
+                        nonTrivRew.second = globalFunctionEliminationVisitor.eliminate(nonTrivRew.second);
+                    }
                 }
                 
                 void traverse(Automaton& automaton, boost::any const& data) override {
@@ -404,6 +407,11 @@ namespace storm {
             STORM_LOG_ASSERT(!containsFunctionCallExpression(model), "The model still seems to contain function calls.");
         }
         
+        storm::expressions::Expression eliminateFunctionCallsInExpression(storm::expressions::Expression const& expression, Model const& model) {
+            detail::FunctionEliminationExpressionVisitor visitor(&model.getGlobalFunctionDefinitions());
+            return visitor.eliminate(expression);
+        }
+        
     }
 }
 
diff --git a/src/storm/storage/jani/FunctionEliminator.h b/src/storm/storage/jani/FunctionEliminator.h
index 791884aed..c7a3b74eb 100644
--- a/src/storm/storage/jani/FunctionEliminator.h
+++ b/src/storm/storage/jani/FunctionEliminator.h
@@ -5,6 +5,11 @@
 
 
 namespace storm {
+    
+    namespace expressions {
+        class Expression;
+    }
+    
     namespace jani {
         class Model;
         class Property;
@@ -13,6 +18,12 @@ namespace storm {
          * Eliminates all function references in the given model and the given properties by replacing them with their corresponding definitions.
          */
         void eliminateFunctions(Model& model, std::vector<Property>& properties);
+        
+        /*!
+         * Eliminates all function calls in the given expression by replacing them with their corresponding definitions.
+         * Only global function definitions are considered.
+         */
+        storm::expressions::Expression eliminateFunctionCallsInExpression(storm::expressions::Expression const& expression, Model const& model);
 
     }
 }
diff --git a/src/storm/storage/jani/JSONExporter.cpp b/src/storm/storage/jani/JSONExporter.cpp
index bf83d36f0..be2c74471 100644
--- a/src/storm/storage/jani/JSONExporter.cpp
+++ b/src/storm/storage/jani/JSONExporter.cpp
@@ -32,6 +32,8 @@
 #include "storm/storage/jani/Property.h"
 #include "storm/storage/jani/traverser/AssignmentsFinder.h"
 #include "storm/storage/jani/expressions/JaniReduceNestingExpressionVisitor.h"
+#include "storm/storage/jani/FunctionEliminator.h"
+#include "storm/storage/jani/expressions/JaniExpressionSubstitutionVisitor.h"
 
 namespace storm {
     namespace jani {
@@ -162,20 +164,35 @@ namespace storm {
         }
         
         modernjson::json FormulaToJaniJson::constructRewardAccumulation(storm::logic::RewardAccumulation const& rewardAccumulation, std::string const& rewardModelName) const {
+            bool steps = false;
+            bool time = false;
+            bool exit = false;
             
-            storm::jani::Variable const& transientVar = model.getGlobalVariable(rewardModelName);
-            storm::jani::AssignmentsFinder::ResultType assignmentKinds;
-            STORM_LOG_THROW(model.hasGlobalVariable(rewardModelName), storm::exceptions::InvalidPropertyException, "Unable to find transient variable with name " << rewardModelName << ".");
-            if (transientVar.getInitExpression().containsVariables() || !storm::utility::isZero(transientVar.getInitExpression().evaluateAsRational())) {
-                assignmentKinds.hasLocationAssignment = true;
-                assignmentKinds.hasEdgeAssignment = true;
-                assignmentKinds.hasEdgeDestinationAssignment = true;
+            auto rewardExpression = storm::jani::eliminateFunctionCallsInExpression(model.getRewardModelExpression(rewardModelName), model);
+            
+            auto variablesInRewardExpression = rewardExpression.getVariables();
+            std::map<storm::expressions::Variable, storm::expressions::Expression> initialSubstitution;
+            for (auto const& v : variablesInRewardExpression) {
+                STORM_LOG_ASSERT(model.hasGlobalVariable(v.getName()), "Unable to find global variable " << v.getName() << " occurring in a reward expression.");
+                auto const& janiVar = model.getGlobalVariable(v.getName());
+                if (janiVar.hasInitExpression()) {
+                    initialSubstitution.emplace(v, janiVar.getInitExpression());
+                }
+                auto assignmentKinds = storm::jani::AssignmentsFinder().find(model, v);
+                steps = steps || assignmentKinds.hasEdgeAssignment || assignmentKinds.hasEdgeDestinationAssignment;
+                time = time || (!model.isDeterministicModel() && assignmentKinds.hasLocationAssignment);
+                exit = exit || assignmentKinds.hasLocationAssignment;
             }
-            assignmentKinds = storm::jani::AssignmentsFinder().find(model, transientVar);
-
-            bool steps = rewardAccumulation.isStepsSet() && (assignmentKinds.hasEdgeAssignment || assignmentKinds.hasEdgeDestinationAssignment);
-            bool time = rewardAccumulation.isTimeSet() && !model.isDiscreteTimeModel() && assignmentKinds.hasLocationAssignment;
-            bool exit = rewardAccumulation.isExitSet() && assignmentKinds.hasLocationAssignment;
+            storm::jani::substituteJaniExpression(rewardExpression, initialSubstitution);
+            if (rewardExpression.containsVariables() || !storm::utility::isZero(rewardExpression.evaluateAsRational())) {
+                steps = true;
+                time = true;
+                exit = true;
+            }
+            
+            steps = steps && rewardAccumulation.isStepsSet();
+            time = time && rewardAccumulation.isTimeSet();
+            exit = exit && rewardAccumulation.isExitSet();
             return constructRewardAccumulation(storm::logic::RewardAccumulation(steps, time, exit));
         }
         
@@ -265,7 +282,7 @@ namespace storm {
                     opDecl["step-bounds"] = propertyInterval;
                 } else if(tbr.isRewardBound()) {
                     modernjson::json rewbound;
-                    rewbound["exp"] = tbr.getRewardName();
+                    rewbound["exp"] = buildExpression(model.getRewardModelExpression(tbr.getRewardName()), model.getConstants(), model.getGlobalVariables());
                     if (tbr.hasRewardAccumulation()) {
                         rewbound["accumulate"] = constructRewardAccumulation(tbr.getRewardAccumulation(), tbr.getRewardName());
                     } else {
@@ -512,7 +529,7 @@ namespace storm {
                     opDecl["left"][instantName] = buildExpression(f.getSubformula().asInstantaneousRewardFormula().getBound(), model.getConstants(), model.getGlobalVariables());
                 }
                 STORM_LOG_THROW(f.hasRewardModelName(), storm::exceptions::NotSupportedException, "Reward name has to be specified for Jani-conversion");
-                opDecl["left"]["exp"] = rewardModelName;
+                opDecl["left"]["exp"] = buildExpression(model.getRewardModelExpression(rewardModelName), model.getConstants(), model.getGlobalVariables());
                 opDecl["right"] = buildExpression(bound.threshold, model.getConstants(), model.getGlobalVariables());
             } else {
                 if (f.hasOptimalityType()) {
@@ -541,7 +558,7 @@ namespace storm {
                 } else if (f.getSubformula().isInstantaneousRewardFormula()) {
                     opDecl[instantName] = buildExpression(f.getSubformula().asInstantaneousRewardFormula().getBound(), model.getConstants(), model.getGlobalVariables());
                 }
-                opDecl["exp"] = rewardModelName;
+                opDecl["exp"] = buildExpression(model.getRewardModelExpression(rewardModelName), model.getConstants(), model.getGlobalVariables());
             }
             return opDecl;
         }
diff --git a/src/storm/storage/jani/Model.cpp b/src/storm/storage/jani/Model.cpp
index 2e9a981d3..79a37d384 100644
--- a/src/storm/storage/jani/Model.cpp
+++ b/src/storm/storage/jani/Model.cpp
@@ -79,6 +79,7 @@ namespace storm {
                 this->constants = other.constants;
                 this->constantToIndex = other.constantToIndex;
                 this->globalVariables = other.globalVariables;
+                this->nonTrivialRewardModels = other.nonTrivialRewardModels;
                 this->automata = other.automata;
                 this->automatonToIndex = other.automatonToIndex;
                 this->composition = other.composition;
@@ -435,6 +436,8 @@ namespace storm {
             
             // Otherwise, we need to actually flatten composition.
             Model flattenedModel(this->getName() + "_flattened", this->getModelType(), this->getJaniVersion(), this->getManager().shared_from_this());
+            
+            flattenedModel.getModelFeatures() = getModelFeatures();
 
             // Get an SMT solver for computing possible guard combinations.
             std::unique_ptr<storm::solver::SmtSolver> solver = smtSolverFactory->create(*expressionManager);
@@ -463,6 +466,14 @@ namespace storm {
                 flattenedModel.addConstant(constant);
             }
             
+            for (auto const& nonTrivRew : getNonTrivialRewardExpressions()) {
+                flattenedModel.addNonTrivialRewardExpression(nonTrivRew.first, nonTrivRew.second);
+            }
+            
+            for (auto const& funDef : getGlobalFunctionDefinitions()) {
+                flattenedModel.addFunctionDefinition(funDef.second);
+            }
+
             std::vector<std::reference_wrapper<Automaton const>> composedAutomata;
             for (auto const& element : parallelComposition.getSubcompositions()) {
                 STORM_LOG_THROW(element->isAutomatonComposition(), storm::exceptions::WrongFormatException, "Cannot flatten recursive (not standard-compliant) composition.");
@@ -558,6 +569,9 @@ namespace storm {
                 if (automaton.get().hasInitialStatesRestriction()) {
                     initialStatesRestriction = initialStatesRestriction && automaton.get().getInitialStatesRestriction();
                 }
+                for (auto const& funDef : automaton.get().getFunctionDefinitions()) {
+                    newAutomaton.addFunctionDefinition(funDef.second);
+                }
             }
             
             newAutomaton.setInitialStatesRestriction(this->getInitialStatesExpression(composedAutomata));
@@ -748,7 +762,63 @@ namespace storm {
         storm::expressions::ExpressionManager& Model::getExpressionManager() const {
             return *expressionManager;
         }
-
+        
+        bool Model::addNonTrivialRewardExpression(std::string const& identifier, storm::expressions::Expression const& rewardExpression) {
+            if (nonTrivialRewardModels.count(identifier) > 0) {
+                return false;
+            } else {
+                nonTrivialRewardModels.emplace(identifier, rewardExpression);
+                return true;
+            }
+        }
+        
+        storm::expressions::Expression Model::getRewardModelExpression(std::string const& identifier) const {
+            auto findRes = nonTrivialRewardModels.find(identifier);
+            if (findRes != nonTrivialRewardModels.end()) {
+                return findRes->second;
+            } else {
+                // Check whether the reward model refers to a global variable
+                if (globalVariables.hasVariable(identifier)) {
+                    return globalVariables.getVariable(identifier).getExpressionVariable().getExpression();
+                } else {
+                    STORM_LOG_THROW(identifier.empty(), storm::exceptions::InvalidArgumentException, "Cannot find unknown reward model '" << identifier << "'.");
+                    STORM_LOG_THROW(nonTrivialRewardModels.size() + globalVariables.getNumberOfNumericalTransientVariables() == 1, storm::exceptions::InvalidArgumentException, "Reference to standard reward model is ambiguous.");
+                    if (nonTrivialRewardModels.size() == 1) {
+                        return nonTrivialRewardModels.begin()->second;
+                    } else {
+                        for (auto const& variable : globalVariables.getTransientVariables()) {
+                            if (variable.isRealVariable() || variable.isUnboundedIntegerVariable() || variable.isBoundedIntegerVariable()) {
+                                return variable.getExpressionVariable().getExpression();
+                            }
+                        }
+                    }
+                }
+            }
+            STORM_LOG_THROW(false, storm::exceptions::InvalidArgumentException, "Cannot find unknown reward model '" << identifier << "'.");
+            return storm::expressions::Expression();
+        }
+        
+        std::vector<std::pair<std::string, storm::expressions::Expression>> Model::getAllRewardModelExpressions() const {
+            std::vector<std::pair<std::string, storm::expressions::Expression>> result;
+            for (auto const& nonTrivExpr : nonTrivialRewardModels) {
+                result.emplace_back(nonTrivExpr.first, nonTrivExpr.second);
+            }
+            for (auto const& variable : globalVariables.getTransientVariables()) {
+                if (variable.isRealVariable() || variable.isUnboundedIntegerVariable() || variable.isBoundedIntegerVariable()) {
+                    result.emplace_back(variable.getName(), variable.getExpressionVariable().getExpression());
+                }
+            }
+            return result;
+        }
+        
+        std::unordered_map<std::string, storm::expressions::Expression> const& Model::getNonTrivialRewardExpressions() const {
+            return nonTrivialRewardModels;
+        }
+        
+        std::unordered_map<std::string, storm::expressions::Expression>& Model::getNonTrivialRewardExpressions() {
+            return nonTrivialRewardModels;
+        }
+        
         uint64_t Model::addAutomaton(Automaton const& automaton) {
             auto it = automatonToIndex.find(automaton.getName());
             STORM_LOG_THROW(it == automatonToIndex.end(), storm::exceptions::WrongFormatException, "Automaton with name '" << automaton.getName() << "' already exists.");
@@ -947,6 +1017,10 @@ namespace storm {
             // Substitute constants in initial states expression.
             result.setInitialStatesRestriction(substituteJaniExpression(this->getInitialStatesRestriction(), constantSubstitution));
             
+            for (auto& rewMod : result.getNonTrivialRewardExpressions()) {
+                rewMod.second = substituteJaniExpression(rewMod.second, constantSubstitution);
+            }
+            
             // Substitute constants in variables of automata and their edges.
             for (auto& automaton : result.getAutomata()) {
                 automaton.substitute(constantSubstitution);
@@ -996,6 +1070,10 @@ namespace storm {
             // Substitute in initial states expression.
             this->setInitialStatesRestriction(substituteJaniExpression(this->getInitialStatesRestriction(), substitution));
             
+            for (auto& rewMod : getNonTrivialRewardExpressions()) {
+                rewMod.second = substituteJaniExpression(rewMod.second, substitution);
+            }
+
             // Substitute in variables of automata and their edges.
             for (auto& automaton : this->getAutomata()) {
                 automaton.substitute(substitution);
diff --git a/src/storm/storage/jani/Model.h b/src/storm/storage/jani/Model.h
index 0eff007e5..c0740a80c 100644
--- a/src/storm/storage/jani/Model.h
+++ b/src/storm/storage/jani/Model.h
@@ -270,6 +270,33 @@ namespace storm {
              */
             storm::expressions::ExpressionManager& getExpressionManager() const;
 
+            /*!
+             * Adds a (non-trivial) reward model, i.e., a reward model that does not consist of a single, global, numerical variable.
+             * @return true if a new reward model was added and false if a reward model with this identifier is already present in the model (in which case no reward model is added)
+             */
+            bool addNonTrivialRewardExpression(std::string const& identifier, storm::expressions::Expression const& rewardExpression);
+            
+            /*!
+             * Retrieves the defining reward expression of the reward model with the given identifier.
+             */
+             storm::expressions::Expression getRewardModelExpression(std::string const& identifier) const;
+            
+            /*!
+             * Retrieves all available reward model names and expressions of the model.
+             * This includes defined non-trivial reward expressions as well as transient, global, numerical variables
+             */
+             std::vector<std::pair<std::string, storm::expressions::Expression>> getAllRewardModelExpressions() const;
+            
+            /*!
+             * Retrieves all available non-trivial reward model names and expressions of the model.
+             */
+             std::unordered_map<std::string, storm::expressions::Expression> const& getNonTrivialRewardExpressions() const;
+            
+            /*!
+             * Retrieves all available non-trivial reward model names and expressions of the model.
+             */
+             std::unordered_map<std::string, storm::expressions::Expression>& getNonTrivialRewardExpressions();
+            
             /*!
              * Adds the given automaton to the automata of this model.
              */
@@ -614,6 +641,10 @@ namespace storm {
             /// A mapping from names to action indices.
             std::unordered_map<std::string, uint64_t> actionToIndex;
             
+            /// A mapping from non-trivial reward model names to their defining expression.
+            /// (A reward model is trivial, if it is represented by a single, global, numeric variable)
+            std::unordered_map<std::string, storm::expressions::Expression> nonTrivialRewardModels;
+            
             /// The set of non-silent action indices.
             boost::container::flat_set<uint64_t> nonsilentActionIndices;
             
diff --git a/src/storm/storage/jani/VariableSet.cpp b/src/storm/storage/jani/VariableSet.cpp
index f6a47e34c..a3af625d5 100644
--- a/src/storm/storage/jani/VariableSet.cpp
+++ b/src/storm/storage/jani/VariableSet.cpp
@@ -280,6 +280,16 @@ namespace storm {
             return result;
         }
         
+        uint_fast64_t VariableSet::getNumberOfNumericalTransientVariables() const {
+            uint_fast64_t result = 0;
+            for (auto const& variable : transientVariables) {
+                if (variable->isRealVariable() || variable->isUnboundedIntegerVariable() || variable->isBoundedIntegerVariable()) {
+                    ++result;
+                }
+            }
+            return result;
+        }
+        
         typename detail::ConstVariables<Variable> VariableSet::getTransientVariables() const {
             return detail::ConstVariables<Variable>(transientVariables.begin(), transientVariables.end());
         }
diff --git a/src/storm/storage/jani/VariableSet.h b/src/storm/storage/jani/VariableSet.h
index 227535e6f..4e4d2d511 100644
--- a/src/storm/storage/jani/VariableSet.h
+++ b/src/storm/storage/jani/VariableSet.h
@@ -218,6 +218,11 @@ namespace storm {
              */
             uint_fast64_t getNumberOfUnboundedIntegerTransientVariables() const;
 
+            /*!
+             * Retrieves the number of numerical (i.e. real, or integer) transient variables in this variable set.
+             */
+            uint_fast64_t getNumberOfNumericalTransientVariables() const;
+
             /*!
              * Retrieves the transient variables in this variable set.
              */
diff --git a/src/storm/storage/jani/traverser/JaniTraverser.cpp b/src/storm/storage/jani/traverser/JaniTraverser.cpp
index 72f979b2d..7682c9a88 100644
--- a/src/storm/storage/jani/traverser/JaniTraverser.cpp
+++ b/src/storm/storage/jani/traverser/JaniTraverser.cpp
@@ -21,6 +21,9 @@ namespace storm {
             if (model.hasInitialStatesRestriction()) {
                 traverse(model.getInitialStatesRestriction(), data);
             }
+            for (auto& nonTrivRew : model.getNonTrivialRewardExpressions()) {
+                traverse(nonTrivRew.second, data);
+            }
         }
         
         void JaniTraverser::traverse(Action const& action, boost::any const& data) {
@@ -184,6 +187,9 @@ namespace storm {
             if (model.hasInitialStatesRestriction()) {
                 traverse(model.getInitialStatesRestriction(), data);
             }
+            for (auto const& nonTrivRew : model.getNonTrivialRewardExpressions()) {
+                traverse(nonTrivRew.second, data);
+            }
         }
         
         void ConstJaniTraverser::traverse(Action const& action, boost::any const& data) {