diff --git a/src/storm/storage/dd/bisimulation/SignatureRefiner.cpp b/src/storm/storage/dd/bisimulation/SignatureRefiner.cpp
index 3083ea75d..e5c11b3d3 100644
--- a/src/storm/storage/dd/bisimulation/SignatureRefiner.cpp
+++ b/src/storm/storage/dd/bisimulation/SignatureRefiner.cpp
@@ -27,8 +27,11 @@
 #include "sylvan_table.h"
 #include "sylvan_int.h"
 
-// FIXME: remove
-#include "storm/storage/dd/DdManager.h"
+#ifdef STORM_HAVE_INTELTBB
+#include "tbb/tbb.h"
+#else
+#error "Need TBB at this point."
+#endif
 
 namespace storm {
     namespace dd {
@@ -471,6 +474,23 @@ namespace storm {
             template<storm::dd::DdType DdType>
             class InternalSignatureRefinerBase;
             
+            struct MutexWrapper {
+                MutexWrapper() : mutex() {
+                    // Intentionally left empty.
+                }
+                
+                MutexWrapper(MutexWrapper const& other) {
+                    // Intentionally left empty to create new mutex when copying.
+                }
+                
+                MutexWrapper& operator=(MutexWrapper const& other) {
+                    // Intentionally left empty to create new mutex when copying.
+                    return *this;
+                }
+                
+                std::mutex mutex;
+            };
+            
             template<>
             class InternalSignatureRefinerBase<storm::dd::DdType::Sylvan> {
             public:
@@ -513,10 +533,12 @@ namespace storm {
                 
                 // The cache used to identify states with identical signature.
                 spp::sparse_hash_map<std::pair<MTBDD, MTBDD>, std::pair<BDD, BDD>, SylvanMTBDDPairHash> signatureCache;
-                spp::sparse_hash_map<std::pair<MTBDD, MTBDD>, BDD, SylvanMTBDDPairHash> signatureCacheSingle;
-                
+//                spp::sparse_hash_map<std::pair<MTBDD, MTBDD>, std::pair<BDD, MutexWrapper>, SylvanMTBDDPairHash> signatureCacheParallel;
+                tbb::concurrent_unordered_map<std::pair<MTBDD, MTBDD>, std::pair<BDD, std::unique_ptr<std::mutex>>, SylvanMTBDDPairHash> signatureCacheParallel;
+
                 // The cache used to identify which old block numbers have already been reused.
                 spp::sparse_hash_map<MTBDD, ReuseWrapper> reuseBlocksCache;
+                tbb::concurrent_unordered_map<MTBDD, ReuseWrapper> reuseBlocksCacheParallel;
 
                 // A mutex that can be used to synchronize concurrent accesses to the members.
                 std::mutex mutex;
@@ -538,8 +560,9 @@ namespace storm {
                 
                 void clearCaches() {
                     signatureCache.clear();
-                    signatureCacheSingle.clear();
+                    signatureCacheParallel.clear();
                     reuseBlocksCache.clear();
+                    reuseBlocksCacheParallel.clear();
                 }
                 
                 std::pair<storm::dd::Bdd<storm::dd::DdType::Sylvan>, boost::optional<storm::dd::Bdd<storm::dd::DdType::Sylvan>>> refine(Partition<storm::dd::DdType::Sylvan, ValueType> const& oldPartition, storm::dd::Add<storm::dd::DdType::Sylvan, ValueType> const& signatureAdd) {
@@ -602,7 +625,6 @@ namespace storm {
                             auto& reuseBlockEntry = reuseBlocksCache[partitionNode];
                             if (!reuseBlockEntry.isReused()) {
                                 reuseBlockEntry.setReused();
-                                reuseBlocksCache.emplace(partitionNode, true);
                                 std::pair<BDD, BDD> result;
                                 if (options.createChangedStates) {
                                     result = std::make_pair(partitionNode, sylvan_false);
@@ -750,7 +772,6 @@ namespace storm {
                             auto& reuseBlockEntry = reuseBlocksCache[partitionNode];
                             if (!reuseBlockEntry.isReused()) {
                                 reuseBlockEntry.setReused();
-                                reuseBlocksCache.emplace(partitionNode, true);
                                 std::pair<BDD, BDD> result;
                                 if (options.createChangedStates) {
                                     result = std::make_pair(partitionNode, sylvan_false);
@@ -888,34 +909,38 @@ namespace storm {
                 }
                 
                 if (sylvan_isconst(nonBlockVariablesNode)) {
-                    // Get the lock so we can modify the signature cache.
+                    auto nodePair = std::make_pair(signatureNode, partitionNode);
+
                     lock.lock();
+                    auto& signatureCacheEntry = refiner.signatureCacheParallel[nodePair];
                     
-                    // Check the signature cache whether we have seen this signature before.
-                    auto nodePair = std::make_pair(signatureNode, partitionNode);
-                    auto it = refiner.signatureCacheSingle.find(nodePair);
-                    if (it != refiner.signatureCacheSingle.end()) {
-                        return it->second;
+                    // If the mutex already exists, it means that some other thread has created it and this thread is
+                    // supposed to yield the right answer. We can therefore wait for this lock and then return the result.
+                    if (signatureCacheEntry.second) {
+                        std::unique_lock<std::mutex> blockLock(*signatureCacheEntry.second);
+                        return signatureCacheEntry.first;
+                    } else {
+                        signatureCacheEntry.second = std::make_unique<std::mutex>();
                     }
-                    
+                    std::unique_lock<std::mutex> blockLock(*signatureCacheEntry.second);
+                    lock.unlock();
+
                     if (refiner.options.reuseBlockNumbers) {
                         // If this is the first time (in this traversal) that we encounter this signature, we check
                         // whether we can assign the old block number to it.
                         
-                        auto& reuseBlockEntry = refiner.reuseBlocksCache[partitionNode];
+                        auto& reuseBlockEntry = refiner.reuseBlocksCacheParallel[partitionNode];
                         if (!reuseBlockEntry.isReused()) {
                             reuseBlockEntry.setReused();
-                            refiner.reuseBlocksCache.emplace(partitionNode, true);
-                            refiner.signatureCacheSingle[nodePair] = partitionNode;
+                            signatureCacheEntry.first = partitionNode;
                             return partitionNode;
                         }
                     }
-                    
-                    // Encode new block and give up lock before 
+
                     result = refiner.encodeBlock(refiner.nextFreeBlockIndex++);
-                    refiner.signatureCacheSingle[nodePair] = result;
-                    lock.unlock();
-                    
+                    signatureCacheEntry.first = result;
+                    blockLock.unlock();
+
                     // Store the result in the cache.
                     cache_put(signatureNode|(256LL<<42), nonBlockVariablesNode, partitionNode|(refiner.numberOfRefinements<<40), result);