diff --git a/src/builder/jit/StateBehaviour.cpp b/src/builder/jit/StateBehaviour.cpp
index 6ad82405e..ddb976a96 100644
--- a/src/builder/jit/StateBehaviour.cpp
+++ b/src/builder/jit/StateBehaviour.cpp
@@ -133,8 +133,8 @@ namespace storm {
                             // If there is no previous Markovian choice, just move the Markovian choice to the front.
                             if (index != 0) {
                                 std::swap(choices.front(), choice);
-                                foundPreviousMarkovianChoice = true;
                             }
+                            foundPreviousMarkovianChoice = true;
                             ++index;
                         }
                     } else {
diff --git a/src/generator/JaniNextStateGenerator.cpp b/src/generator/JaniNextStateGenerator.cpp
index 2cf113f7d..539e01d9f 100644
--- a/src/generator/JaniNextStateGenerator.cpp
+++ b/src/generator/JaniNextStateGenerator.cpp
@@ -390,6 +390,9 @@ namespace storm {
             // Iterate over all automata.
             uint64_t automatonIndex = 0;
             
+            std::cout << "getting silent choices of state" << std::endl;
+            std::cout << unpackStateIntoValuation(state, this->variableInformation, *this->expressionManager).toString(true) << std::endl;
+            
             for (auto const& automaton : model.getAutomata()) {
                 uint64_t location = locations[automatonIndex];
                 
@@ -402,8 +405,10 @@ namespace storm {
                     
                     // Skip the command, if it is not enabled.
                     if (!this->evaluator->asBool(edge.getGuard())) {
+                        std::cout << "guard " << edge.getGuard() << " evaluates to false" << std::endl;
                         continue;
                     }
+                    std::cout << "guard " << edge.getGuard() << " evaluates to true" << std::endl;
                     
                     // Determine the exit rate if it's a Markovian edge.
                     boost::optional<ValueType> exitRate = boost::none;
@@ -422,6 +427,7 @@ namespace storm {
                         if (probability != storm::utility::zero<ValueType>()) {
                             // Obtain target state index and add it to the list of known states. If it has not yet been
                             // seen, we also add it to the set of states that have yet to be explored.
+                            std::cout << "got new state " << unpackStateIntoValuation(applyUpdate(state, destination, this->variableInformation.locationVariables[automatonIndex]), this->variableInformation, *this->expressionManager).toString(true) << std::endl;
                             StateType stateIndex = stateToIdCallback(applyUpdate(state, destination, this->variableInformation.locationVariables[automatonIndex]));
                             
                             // Update the choice by adding the probability/target state to it.
@@ -453,6 +459,9 @@ namespace storm {
         std::vector<Choice<ValueType>> JaniNextStateGenerator<ValueType, StateType>::getNonsilentActionChoices(std::vector<uint64_t> const& locations, CompressedState const& state, StateToIdCallback stateToIdCallback) {
             std::vector<Choice<ValueType>> result;
             
+            std::cout << "getting nonsilent choices of state" << std::endl;
+            std::cout << unpackStateIntoValuation(state, this->variableInformation, *this->expressionManager).toString(true) << std::endl;
+            
             for (uint64_t actionIndex : model.getNonsilentActionIndices()) {
                 std::vector<std::vector<storm::jani::Edge const*>> enabledEdges = getEnabledEdges(locations, actionIndex);
                 
@@ -530,9 +539,14 @@ namespace storm {
                         // Add the probabilities/rates to the newly created choice.
                         ValueType probabilitySum = storm::utility::zero<ValueType>();
                         for (auto const& stateProbabilityPair : *newTargetStates) {
+                            std::cout << "got new state (sync)" << std::endl;
+                            std::cout << unpackStateIntoValuation(stateProbabilityPair.first, this->variableInformation, *this->expressionManager).toString(true) << std::endl;
                             StateType actualIndex = stateToIdCallback(stateProbabilityPair.first);
                             choice.addProbability(actualIndex, stateProbabilityPair.second);
-                            probabilitySum += stateProbabilityPair.second;
+                            
+                            if (this->options.isExplorationChecksSet()) {
+                                probabilitySum += stateProbabilityPair.second;
+                            }
                         }
                         
                         if (this->options.isExplorationChecksSet()) {
diff --git a/src/generator/NextStateGenerator.cpp b/src/generator/NextStateGenerator.cpp
index 0c2d62601..8c13d62d8 100644
--- a/src/generator/NextStateGenerator.cpp
+++ b/src/generator/NextStateGenerator.cpp
@@ -127,8 +127,8 @@ namespace storm {
                             // If there is no previous Markovian choice, just move the Markovian choice to the front.
                             if (index != 0) {
                                 std::swap(result.getChoices().front(), choice);
-                                foundPreviousMarkovianChoice = true;
                             }
+                            foundPreviousMarkovianChoice = true;
                             ++index;
                         }
                     } else {
diff --git a/src/generator/PrismNextStateGenerator.cpp b/src/generator/PrismNextStateGenerator.cpp
index b9fa22957..da6c32214 100644
--- a/src/generator/PrismNextStateGenerator.cpp
+++ b/src/generator/PrismNextStateGenerator.cpp
@@ -385,7 +385,7 @@ namespace storm {
                     if (!this->evaluator->asBool(command.getGuardExpression())) {
                         continue;
                     }
-                    
+                                        
                     result.push_back(Choice<ValueType>(command.getActionIndex(), command.isMarkovian()));
                     Choice<ValueType>& choice = result.back();
                     
@@ -407,7 +407,9 @@ namespace storm {
                             
                             // Update the choice by adding the probability/target state to it.
                             choice.addProbability(stateIndex, probability);
-                            probabilitySum += probability;
+                            if (this->options.isExplorationChecksSet()) {
+                                probabilitySum += probability;
+                            }
                         }
                     }
                     
diff --git a/src/storage/expressions/SimpleValuation.cpp b/src/storage/expressions/SimpleValuation.cpp
index 2f241958a..e92251f54 100644
--- a/src/storage/expressions/SimpleValuation.cpp
+++ b/src/storage/expressions/SimpleValuation.cpp
@@ -110,27 +110,16 @@ namespace storm {
             return "[" + boost::join(assignments, ", ") + "]";
         }
 
-
         std::string SimpleValuation::toString(bool pretty) const {
-            std::stringstream sstr;
-            if(pretty) {
-                sstr << "valuation {" << std::endl;
-                for(auto const& e : getManager()) {
-                    sstr << e.first.getName() << "=";
-                    if (e.first.hasBooleanType()) {
-                        sstr << std::boolalpha << this->getBooleanValue(e.first) << std::noboolalpha;
-                    } else if (e.first.hasIntegerType()) {
-                        sstr << this->getIntegerValue(e.first);
-                    } else if (e.first.hasRationalType()) {
-                        sstr << this->getRationalValue(e.first);
-                    } else {
-                        STORM_LOG_THROW(false, storm::exceptions::InvalidTypeException, "Unexpected variable type.");
-                    }
-                    sstr << std::endl;
+            if (pretty) {
+                std::set<storm::expressions::Variable> allVariables;
+                for (auto const& e : getManager()) {
+                    allVariables.insert(e.first);
                 }
-                sstr << "}";
+                return toPrettyString(allVariables);
             } else {
-                sstr << "valuation {" << std::endl;
+                std::stringstream sstr;
+                sstr << "[" << std::endl;
                 sstr << getManager() << std::endl;
                 if (!booleanValues.empty()) {
                     for (auto const& element : booleanValues) {
@@ -150,11 +139,9 @@ namespace storm {
                     }
                     sstr << std::endl;
                 }
-                sstr << "}";
+                sstr << "]";
+                return sstr.str();
             }
-
-
-            return sstr.str();
         }
         
         std::ostream& operator<<(std::ostream& out, SimpleValuation const& valuation) {
diff --git a/src/utility/storm.h b/src/utility/storm.h
index 7d8ac5526..14176636e 100644
--- a/src/utility/storm.h
+++ b/src/utility/storm.h
@@ -226,7 +226,7 @@ namespace storm {
         if (model->getType() == storm::models::ModelType::MarkovAutomaton && model->isSparseModel()) {
             std::shared_ptr<storm::models::sparse::MarkovAutomaton<typename ModelType::ValueType>> ma = model->template as<storm::models::sparse::MarkovAutomaton<typename ModelType::ValueType>>();
             if (ma->hasOnlyTrivialNondeterminism()) {
-                // Markov automaton can be converted into CTMC
+                // Markov automaton can be converted into CTMC.
                 model = ma->convertToCTMC();
             }
         }