diff --git a/src/storm-pomdp/builder/BeliefMdpExplorer.h b/src/storm-pomdp/builder/BeliefMdpExplorer.h
index 33e1d1f51..86f49fe02 100644
--- a/src/storm-pomdp/builder/BeliefMdpExplorer.h
+++ b/src/storm-pomdp/builder/BeliefMdpExplorer.h
@@ -29,12 +29,20 @@ namespace storm {
             typedef typename BeliefManagerType::BeliefId BeliefId;
             typedef uint64_t MdpStateType;
             
-            BeliefMdpExplorer(std::shared_ptr<BeliefManagerType> beliefManager, std::vector<ValueType> const& pomdpLowerValueBounds, std::vector<ValueType> const& pomdpUpperValueBounds) : beliefManager(beliefManager), pomdpLowerValueBounds(pomdpLowerValueBounds), pomdpUpperValueBounds(pomdpUpperValueBounds) {
+            enum class Status {
+                Uninitialized,
+                Exploring,
+                ModelFinished,
+                ModelChecked
+            };
+            
+            BeliefMdpExplorer(std::shared_ptr<BeliefManagerType> beliefManager, std::vector<ValueType> const& pomdpLowerValueBounds, std::vector<ValueType> const& pomdpUpperValueBounds) : beliefManager(beliefManager), pomdpLowerValueBounds(pomdpLowerValueBounds), pomdpUpperValueBounds(pomdpUpperValueBounds), status(Status::Uninitialized) {
                 // Intentionally left empty
             }
             BeliefMdpExplorer(BeliefMdpExplorer&& other) = default;
 
             void startNewExploration(boost::optional<ValueType> extraTargetStateValue = boost::none, boost::optional<ValueType> extraBottomStateValue = boost::none) {
+                status = Status::Exploring;
                 // Reset data from potential previous explorations
                 mdpStateToBeliefIdMap.clear();
                 beliefIdToMdpStateMap.clear();
@@ -83,10 +91,12 @@ namespace storm {
             }
     
             bool hasUnexploredState() const {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 return !beliefIdsToExplore.empty();
             }
     
             BeliefId exploreNextState() {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 // Set up the matrix builder
                 finishCurrentRow();
                 startOfCurrentRowGroup = currentRowCount;
@@ -100,6 +110,7 @@ namespace storm {
             }
             
             void addTransitionsToExtraStates(uint64_t const& localActionIndex, ValueType const& targetStateValue = storm::utility::zero<ValueType>(), ValueType const& bottomStateValue = storm::utility::zero<ValueType>()) {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 // We first insert the entries of the current row in a separate map.
                 // This is to ensure that entries are sorted in the right way (as required for the transition matrix builder)
                 
@@ -115,6 +126,7 @@ namespace storm {
             }
             
             void addSelfloopTransition(uint64_t const& localActionIndex = 0, ValueType const& value = storm::utility::one<ValueType>()) {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 uint64_t row = startOfCurrentRowGroup + localActionIndex;
                 internalAddTransition(row, getCurrentMdpState(), value);
             }
@@ -128,6 +140,7 @@ namespace storm {
              * @return true iff a transition was actually inserted. False can only happen if ignoreNewBeliefs is true.
              */
             bool addTransitionToBelief(uint64_t const& localActionIndex, BeliefId const& transitionTarget, ValueType const& value, bool ignoreNewBeliefs) {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 // We first insert the entries of the current row in a separate map.
                 // This is to ensure that entries are sorted in the right way (as required for the transition matrix builder)
                 MdpStateType column;
@@ -145,6 +158,7 @@ namespace storm {
             }
             
             void computeRewardAtCurrentState(uint64 const& localActionIndex, ValueType extraReward = storm::utility::zero<ValueType>()) {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 if (currentRowCount >= mdpActionRewards.size()) {
                     mdpActionRewards.resize(currentRowCount, storm::utility::zero<ValueType>());
                 }
@@ -153,16 +167,19 @@ namespace storm {
             }
             
             void setCurrentStateIsTarget() {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 targetStates.grow(getCurrentNumberOfMdpStates(), false);
                 targetStates.set(getCurrentMdpState(), true);
             }
             
             void setCurrentStateIsTruncated() {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 truncatedStates.grow(getCurrentNumberOfMdpStates(), false);
                 truncatedStates.set(getCurrentMdpState(), true);
             }
             
             void finishExploration() {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 // Create the tranistion matrix
                 finishCurrentRow();
                 auto mdpTransitionMatrix = mdpTransitionsBuilder.build(getCurrentNumberOfMdpChoices(), getCurrentNumberOfMdpStates(), getCurrentNumberOfMdpStates());
@@ -185,26 +202,32 @@ namespace storm {
                 
                 storm::storage::sparse::ModelComponents<ValueType> modelComponents(std::move(mdpTransitionMatrix), std::move(mdpLabeling), std::move(mdpRewardModels));
                 exploredMdp = std::make_shared<storm::models::sparse::Mdp<ValueType>>(std::move(modelComponents));
+                status = Status::ModelFinished;
             }
             
             std::shared_ptr<storm::models::sparse::Mdp<ValueType>> getExploredMdp() const {
+                STORM_LOG_ASSERT(status == Status::ModelFinished || status == Status::ModelChecked, "Method call is invalid in current status.");
                 STORM_LOG_ASSERT(exploredMdp, "Tried to get the explored MDP but exploration was not finished yet.");
                 return exploredMdp;
             }
             
             MdpStateType getCurrentNumberOfMdpStates() const {
+                STORM_LOG_ASSERT(status != Status::Uninitialized, "Method call is invalid in current status.");
                 return mdpStateToBeliefIdMap.size();
             }
     
             MdpStateType getCurrentNumberOfMdpChoices() const {
+                STORM_LOG_ASSERT(status != Status::Uninitialized, "Method call is invalid in current status.");
                 return currentRowCount;
             }
 
             ValueType getLowerValueBoundAtCurrentState() const {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 return lowerValueBounds[getCurrentMdpState()];
             }
 
             ValueType getUpperValueBoundAtCurrentState() const {
+                STORM_LOG_ASSERT(status == Status::Exploring, "Method call is invalid in current status.");
                 return upperValueBounds[getCurrentMdpState()];
             }
 
@@ -216,7 +239,8 @@ namespace storm {
                  return beliefManager->getWeightedSum(beliefId, pomdpUpperValueBounds);
             }
             
-            std::vector<ValueType> const& computeValuesOfExploredMdp(storm::solver::OptimizationDirection const& dir) {
+            void computeValuesOfExploredMdp(storm::solver::OptimizationDirection const& dir) {
+                STORM_LOG_ASSERT(status == Status::ModelFinished, "Method call is invalid in current status.");
                 STORM_LOG_ASSERT(exploredMdp, "Tried to compute values but the MDP is not explored");
                 auto property = createStandardProperty(dir, exploredMdp->hasRewardModel());
                 auto task = createStandardCheckTask(property);
@@ -228,12 +252,18 @@ namespace storm {
                     STORM_LOG_ASSERT(storm::utility::resources::isTerminate(), "Empty check result!");
                     STORM_LOG_ERROR("No result obtained while checking.");
                 }
+                status = Status::ModelChecked;
+            }
+            
+            std::vector<ValueType> const& getValuesOfExploredMdp() const {
+                STORM_LOG_ASSERT(status == Status::ModelChecked, "Method call is invalid in current status.");
                 return values;
             }
             
             ValueType const& getComputedValueAtInitialState() const {
+                STORM_LOG_ASSERT(status == Status::ModelChecked, "Method call is invalid in current status.");
                 STORM_LOG_ASSERT(exploredMdp, "Tried to get a value but no MDP was explored.");
-                return values[exploredMdp->getInitialStates().getNextSetIndex(0)];
+                return getValuesOfExploredMdp()[exploredMdp->getInitialStates().getNextSetIndex(0)];
             }
             
         private:
@@ -355,6 +385,8 @@ namespace storm {
             std::vector<ValueType> upperValueBounds;
             std::vector<ValueType> values; // Contains an estimate during building and the actual result after a check has performed
             
+            // The current status of this explorer
+            Status status;
         };
     }
 }
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