diff --git a/src/storm-pomdp-cli/storm-pomdp.cpp b/src/storm-pomdp-cli/storm-pomdp.cpp
index 181c5c31f..19e139d1d 100644
--- a/src/storm-pomdp-cli/storm-pomdp.cpp
+++ b/src/storm-pomdp-cli/storm-pomdp.cpp
@@ -109,7 +109,9 @@ namespace storm {
                     options.refinementPrecision = storm::utility::convertNumber<ValueType>(gridSettings.getRefinementPrecision());
                     options.numericPrecision = storm::utility::convertNumber<ValueType>(gridSettings.getNumericPrecision());
                     options.cacheSubsimplices = gridSettings.isCacheSimplicesSet();
-                    options.beliefMdpSizeThreshold = gridSettings.getUnfoldBeliefMdpSizeThreshold();
+                    if (gridSettings.isUnfoldBeliefMdpSizeThresholdSet()) {
+                        options.beliefMdpSizeThreshold = gridSettings.getUnfoldBeliefMdpSizeThreshold();
+                    }
                     if (storm::NumberTraits<ValueType>::IsExact) {
                         if (gridSettings.isNumericPrecisionSetFromDefault()) {
                             STORM_LOG_WARN_COND(storm::utility::isZero(options.numericPrecision), "Setting numeric precision to zero because exact arithmethic is used.");
diff --git a/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp b/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp
index 070279ac4..622e63512 100644
--- a/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp
+++ b/src/storm-pomdp/modelchecker/ApproximatePOMDPModelchecker.cpp
@@ -35,7 +35,7 @@ namespace storm {
                 refinementPrecision = storm::utility::convertNumber<ValueType>(1e-4);
                 numericPrecision = storm::NumberTraits<ValueType>::IsExact ? storm::utility::zero<ValueType>() : storm::utility::convertNumber<ValueType>(1e-9);
                 cacheSubsimplices = false;
-                beliefMdpSizeThreshold = 0ull;
+                beliefMdpSizeThreshold = boost::none;
             }
             
             template<typename PomdpModelType, typename BeliefValueType>
@@ -190,7 +190,7 @@ namespace storm {
                         manager->setRewardModel(rewardModelName);
                     }
                     auto approx = std::make_shared<ExplorerType>(manager, lowerPomdpValueBounds, upperPomdpValueBounds);
-                    if (options.beliefMdpSizeThreshold) {
+                    if (options.beliefMdpSizeThreshold && options.beliefMdpSizeThreshold.get() > 0) {
                         underApproxSizeThreshold = options.beliefMdpSizeThreshold.get();
                     }
                     if (underApproxSizeThreshold == 0) {