diff --git a/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp b/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp
index bdf9fab1a..66135c02b 100644
--- a/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp
+++ b/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp
@@ -299,7 +299,6 @@ namespace storm {
                     STORM_PRINT("Exploration threshold: " << explorationThreshold << std::endl)
                 }
                 while (!beliefsToBeExpanded.empty()) {
-                    // TODO direct generation of transition matrix?
                     uint64_t currId = beliefsToBeExpanded.front();
                     beliefsToBeExpanded.pop_front();
                     bool isTarget = beliefIsTarget[currId];
@@ -637,7 +636,7 @@ namespace storm {
                 // Belief ID -> ActionIndex
                 std::map<uint64_t, std::vector<uint64_t>> chosenActions;
 
-                // Belief ID -> Observation -> Probability
+                // Belief ID -> action -> Observation -> Probability
                 std::map<uint64_t, std::vector<std::map<uint32_t, ValueType>>> observationProbabilities;
                 // current ID -> action -> next ID
                 std::map<uint64_t, std::vector<std::map<uint32_t, uint64_t>>> nextBelieves;
@@ -1025,7 +1024,7 @@ namespace storm {
                     storm::models::sparse::Pomdp<ValueType, RewardModelType> const &pomdp,
                     std::set<uint32_t> const &target_observations, uint64_t gridResolution,
                     std::vector<storm::pomdp::Belief<ValueType>> &beliefList,
-                    std::vector<storm::pomdp::Belief<ValueType>> &grid, std::vector<bool> &beliefIsKnown,
+                    std::vector<storm::pomdp::Belief<ValueType>> &grid, std::vector<bool> &beliefIsTarget,
                     uint64_t nextId) {
                 bool isTarget;
                 uint64_t newId = nextId;
@@ -1045,7 +1044,7 @@ namespace storm {
                                               << distribution << "]");
                         beliefList.push_back(belief);
                         grid.push_back(belief);
-                        beliefIsKnown.push_back(isTarget);
+                        beliefIsTarget.push_back(isTarget);
                         ++newId;
                     } else {
                         // Otherwise we have to enumerate all possible distributions with regards to the grid
@@ -1073,7 +1072,7 @@ namespace storm {
                             STORM_LOG_TRACE("Add Belief " << std::to_string(newId) << " [(" << std::to_string(observation) << ")," << distribution << "]");
                             beliefList.push_back(belief);
                             grid.push_back(belief);
-                            beliefIsKnown.push_back(isTarget);
+                            beliefIsTarget.push_back(isTarget);
                             if (helper[statesWithObservation.size() - 1] ==
                                 storm::utility::convertNumber<ValueType>(gridResolution)) {
                                 // If the last entry of helper is the gridResolution, we have enumerated all necessary distributions
@@ -1175,7 +1174,16 @@ namespace storm {
                     uint64_t actionIndex) {
                 std::map<uint32_t, ValueType> res;
                 // the id is not important here as we immediately discard the belief (very hacky, I don't like it either)
-                std::map<uint64_t, ValueType> postProbabilities = getBeliefAfterAction(pomdp, belief, actionIndex, 0).probabilities;
+                std::map<uint64_t, ValueType> postProbabilities;
+                for (auto const &probEntry : belief.probabilities) {
+                    uint64_t state = probEntry.first;
+                    auto row = pomdp.getTransitionMatrix().getRow(pomdp.getChoiceIndex(storm::storage::StateActionPair(state, actionIndex)));
+                    for (auto const &entry : row) {
+                        if (entry.getValue() > 0) {
+                            postProbabilities[entry.getColumn()] += belief.probabilities[state] * entry.getValue();
+                        }
+                    }
+                }
                 for (auto const &probEntry : postProbabilities) {
                     uint32_t observation = pomdp.getObservation(probEntry.first);
                     if (res.count(observation) == 0) {
@@ -1212,7 +1220,6 @@ namespace storm {
                     storm::models::sparse::Pomdp<ValueType, RewardModelType> const &pomdp, std::vector<storm::pomdp::Belief<ValueType>> &beliefList,
                     std::vector<bool> &beliefIsTarget, std::set<uint32_t> const &targetObservations, storm::pomdp::Belief<ValueType> &belief, uint64_t actionIndex,
                     uint32_t observation, uint64_t id) {
-                storm::utility::Stopwatch distrWatch(true);
                 std::map<uint64_t, ValueType> distributionAfter;
                 for (auto const &probEntry : belief.probabilities) {
                     uint64_t state = probEntry.first;
@@ -1223,9 +1230,7 @@ namespace storm {
                         }
                     }
                 }
-                distrWatch.stop();
                 // We have to normalize the distribution
-                storm::utility::Stopwatch normalizationWatch(true);
                 auto sum = storm::utility::zero<ValueType>();
                 for (auto const &entry : distributionAfter) {
                     sum += entry.second;
@@ -1234,19 +1239,12 @@ namespace storm {
                 for (auto const &entry : distributionAfter) {
                     distributionAfter[entry.first] /= sum;
                 }
-                normalizationWatch.stop();
                 if (getBeliefIdInVector(beliefList, observation, distributionAfter) != uint64_t(-1)) {
-                    storm::utility::Stopwatch getWatch(true);
                     auto res = getBeliefIdInVector(beliefList, observation, distributionAfter);
-                    getWatch.stop();
-                    //STORM_PRINT("Distribution: "<< distrWatch.getTimeInNanoseconds() << " / Normalization: " << normalizationWatch.getTimeInNanoseconds() << " / getId: " << getWatch.getTimeInNanoseconds() << std::endl)
                     return res;
                 } else {
-                    storm::utility::Stopwatch pushWatch(true);
                     beliefList.push_back(storm::pomdp::Belief<ValueType>{id, observation, distributionAfter});
                     beliefIsTarget.push_back(targetObservations.find(observation) != targetObservations.end());
-                    pushWatch.stop();
-                    //STORM_PRINT("Distribution: "<< distrWatch.getTimeInNanoseconds() << " / Normalization: " << normalizationWatch.getTimeInNanoseconds() << " / generateBelief: " << pushWatch.getTimeInNanoseconds() << std::endl)
                     return id;
                 }
             }
diff --git a/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.h b/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.h
index 5108d3135..eb3247de1 100644
--- a/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.h
+++ b/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.h
@@ -215,7 +215,7 @@ namespace storm {
                                          std::set<uint32_t> const &target_observations, uint64_t gridResolution,
                                          std::vector<storm::pomdp::Belief<ValueType>> &beliefList,
                                          std::vector<storm::pomdp::Belief<ValueType>> &grid,
-                                         std::vector<bool> &beliefIsKnown, uint64_t nextId);
+                                         std::vector<bool> &beliefIsTarget, uint64_t nextId);
 
 
                 /**