diff --git a/runtime/Cpp/runtime/Parser.cpp b/runtime/Cpp/runtime/Parser.cpp
index 76f587b9c..cc300b11c 100755
--- a/runtime/Cpp/runtime/Parser.cpp
+++ b/runtime/Cpp/runtime/Parser.cpp
@@ -238,7 +238,7 @@ const atn::ATN& Parser::getATNWithBypassAlts() {
     throw UnsupportedOperationException("The current parser does not support an ATN with bypass alternatives.");
   }
 
-  std::lock_guard<std::mutex> lck(mtx);
+  std::lock_guard<std::recursive_mutex> lck(mtx);
 
   // XXX: using the entire serialized ATN as key into the map is a big resource waste.
   //      How large can that thing become?
@@ -572,7 +572,7 @@ std::vector<std::wstring> Parser::getRuleInvocationStack(Ref<RuleContext> p) {
 std::vector<std::wstring> Parser::getDFAStrings() {
   atn::ParserATNSimulator *simulator = getInterpreter<atn::ParserATNSimulator>();
   if (!simulator->decisionToDFA.empty()) {
-    std::lock_guard<std::mutex> lck(mtx);
+    std::lock_guard<std::recursive_mutex> lck(mtx);
 
     std::vector<std::wstring> s;
     for (size_t d = 0; d < simulator->decisionToDFA.size(); d++) {
@@ -587,7 +587,7 @@ std::vector<std::wstring> Parser::getDFAStrings() {
 void Parser::dumpDFA() {
   atn::ParserATNSimulator *simulator = getInterpreter<atn::ParserATNSimulator>();
   if (!simulator->decisionToDFA.empty()) {
-    std::lock_guard<std::mutex> lck(mtx);
+    std::lock_guard<std::recursive_mutex> lck(mtx);
     bool seenOne = false;
     for (size_t d = 0; d < simulator->decisionToDFA.size(); d++) {
       dfa::DFA &dfa = simulator->decisionToDFA[d];
diff --git a/runtime/Cpp/runtime/Parser.h b/runtime/Cpp/runtime/Parser.h
index 6124db1c0..557bfe35b 100755
--- a/runtime/Cpp/runtime/Parser.h
+++ b/runtime/Cpp/runtime/Parser.h
@@ -425,7 +425,7 @@ namespace runtime {
     std::vector<int> _precedenceStack;
     
     //Mutex to manage synchronized access for multithreading in the parser
-    std::mutex mtx;
+    std::recursive_mutex mtx;
 
     /// <summary>
     /// Specifies whether or not the parser should construct a parse tree during
diff --git a/runtime/Cpp/runtime/Recognizer.cpp b/runtime/Cpp/runtime/Recognizer.cpp
index 36e9a8160..3c7a949a0 100755
--- a/runtime/Cpp/runtime/Recognizer.cpp
+++ b/runtime/Cpp/runtime/Recognizer.cpp
@@ -60,7 +60,7 @@ Ref<dfa::Vocabulary> Recognizer::getVocabulary() const {
 std::map<std::wstring, size_t> Recognizer::getTokenTypeMap() {
   Ref<dfa::Vocabulary> vocabulary = getVocabulary();
 
-  std::lock_guard<std::mutex> lck(mtx);
+  std::lock_guard<std::recursive_mutex> lck(mtx);
   std::map<std::wstring, size_t> result;
   auto iterator = _tokenTypeMapCache.find(vocabulary);
   if (iterator != _tokenTypeMapCache.end()) {
@@ -90,7 +90,7 @@ std::map<std::wstring, size_t> Recognizer::getRuleIndexMap() {
     throw L"The current recognizer does not provide a list of rule names.";
   }
 
-  std::lock_guard<std::mutex> lck(mtx);
+  std::lock_guard<std::recursive_mutex> lck(mtx);
   std::map<std::wstring, size_t> result;
   auto iterator = _ruleIndexMapCache.find(ruleNames);
   if (iterator != _ruleIndexMapCache.end()) {
diff --git a/runtime/Cpp/runtime/Recognizer.h b/runtime/Cpp/runtime/Recognizer.h
index 66e3b3277..e64960835 100755
--- a/runtime/Cpp/runtime/Recognizer.h
+++ b/runtime/Cpp/runtime/Recognizer.h
@@ -181,7 +181,7 @@ namespace runtime {
     ProxyErrorListener _proxListener; // Manages a collection of listeners.
 
     // Mutex to manage synchronized access for multithreading.
-    std::mutex mtx;
+    std::recursive_mutex mtx;
 
     int _stateNumber;
     
diff --git a/runtime/Cpp/runtime/atn/ATNSimulator.cpp b/runtime/Cpp/runtime/atn/ATNSimulator.cpp
index a7c5e5a70..d75291389 100755
--- a/runtime/Cpp/runtime/atn/ATNSimulator.cpp
+++ b/runtime/Cpp/runtime/atn/ATNSimulator.cpp
@@ -56,7 +56,7 @@ Ref<PredictionContextCache> ATNSimulator::getSharedContextCache() {
 }
 
 Ref<PredictionContext> ATNSimulator::getCachedContext(Ref<PredictionContext> context) {
-  std::lock_guard<std::mutex> lck(mtx);
+  std::lock_guard<std::recursive_mutex> lck(mtx);
   std::map<Ref<PredictionContext>, Ref<PredictionContext>> visited;
   return PredictionContext::getCachedContext(context, _sharedContextCache, visited);
 }
diff --git a/runtime/Cpp/runtime/atn/ATNSimulator.h b/runtime/Cpp/runtime/atn/ATNSimulator.h
index feadd57de..f775506d2 100755
--- a/runtime/Cpp/runtime/atn/ATNSimulator.h
+++ b/runtime/Cpp/runtime/atn/ATNSimulator.h
@@ -85,7 +85,7 @@ namespace atn {
 
   protected:
     // Mutex to manage synchronized access for multithreading
-    std::mutex mtx;
+    std::recursive_mutex mtx;
 
     /// <summary>
     /// The context cache maps all PredictionContext objects that are equals()
diff --git a/runtime/Cpp/runtime/atn/LexerATNSimulator.cpp b/runtime/Cpp/runtime/atn/LexerATNSimulator.cpp
index b169df0b7..ea5c5283e 100755
--- a/runtime/Cpp/runtime/atn/LexerATNSimulator.cpp
+++ b/runtime/Cpp/runtime/atn/LexerATNSimulator.cpp
@@ -563,7 +563,7 @@ void LexerATNSimulator::addDFAEdge(dfa::DFAState *p, ssize_t t, dfa::DFAState *q
     std::wcout << std::wstring(L"EDGE ") << p << std::wstring(L" -> ") << q << std::wstring(L" upon ") << (static_cast<wchar_t>(t)) << std::endl;
   }
 
-  std::lock_guard<std::mutex> lck(mtx);
+  std::lock_guard<std::recursive_mutex> lck(mtx);
   if (p->edges.empty()) {
     //  make room for tokens 1..n and -1 masquerading as index 0
     p->edges.resize(MAX_DFA_EDGE - MIN_DFA_EDGE + 1);
@@ -595,7 +595,7 @@ dfa::DFAState *LexerATNSimulator::addDFAState(Ref<ATNConfigSet> configs) {
   dfa::DFA &dfa = _decisionToDFA[_mode];
 
   {
-    std::lock_guard<std::mutex> lck(mtx);
+    std::lock_guard<std::recursive_mutex> lck(mtx);
     
     auto iterator = dfa.states.find(proposed);
     if (iterator != dfa.states.end()) {
diff --git a/runtime/Cpp/runtime/atn/ParserATNSimulator.cpp b/runtime/Cpp/runtime/atn/ParserATNSimulator.cpp
index 0c7cbb02f..c95847db5 100755
--- a/runtime/Cpp/runtime/atn/ParserATNSimulator.cpp
+++ b/runtime/Cpp/runtime/atn/ParserATNSimulator.cpp
@@ -1205,7 +1205,7 @@ dfa::DFAState *ParserATNSimulator::addDFAEdge(dfa::DFA &dfa, dfa::DFAState *from
   }
 
   {
-    std::lock_guard<std::mutex> lck(mtx);
+    std::lock_guard<std::recursive_mutex> lck(mtx);
     if (from->edges.empty())
       from->edges.resize(atn.maxTokenType + 1 + 1);
     from->edges[(size_t)(t + 1)] = to; // connect
@@ -1228,7 +1228,7 @@ dfa::DFAState *ParserATNSimulator::addDFAState(dfa::DFA &dfa, dfa::DFAState *D)
   }
 
   {
-    std::lock_guard<std::mutex> lck(mtx);
+    std::lock_guard<std::recursive_mutex> lck(mtx);
 
     auto existing = dfa.states.find(D);
     if (existing != dfa.states.end()) {
diff --git a/runtime/Cpp/runtime/atn/ParserATNSimulator.h b/runtime/Cpp/runtime/atn/ParserATNSimulator.h
index 73a948304..5f044306c 100755
--- a/runtime/Cpp/runtime/atn/ParserATNSimulator.h
+++ b/runtime/Cpp/runtime/atn/ParserATNSimulator.h
@@ -290,7 +290,7 @@ namespace atn {
     PredictionMode mode;
 
     // Mutex to manage synchronized access for multithreading in the parser atn simulator.
-    std::mutex _lock;
+    std::recursive_mutex _lock;
 
     /// <summary>
     /// Each prediction operation uses a cache for merge of prediction contexts.
diff --git a/runtime/Cpp/runtime/dfa/DFA.cpp b/runtime/Cpp/runtime/dfa/DFA.cpp
index 11cd24fe8..387be2956 100755
--- a/runtime/Cpp/runtime/dfa/DFA.cpp
+++ b/runtime/Cpp/runtime/dfa/DFA.cpp
@@ -106,7 +106,7 @@ void DFA::setPrecedenceStartState(int precedence, DFAState *startState) {
 
   // synchronization on s0 here is ok. when the DFA is turned into a
   // precedence DFA, s0 will be initialized once and not updated again
-  std::unique_lock<std::mutex> lock(_lock);
+  std::unique_lock<std::recursive_mutex> lock(_lock);
   {
     // s0.edges is never null for a precedence DFA
     if (precedence >= (int)s0->edges.size()) {
diff --git a/runtime/Cpp/runtime/dfa/DFA.h b/runtime/Cpp/runtime/dfa/DFA.h
index 6ee7d777b..29cadede7 100755
--- a/runtime/Cpp/runtime/dfa/DFA.h
+++ b/runtime/Cpp/runtime/dfa/DFA.h
@@ -109,7 +109,7 @@ namespace dfa {
      */
     bool _precedenceDfa;
 
-    std::mutex _lock; // To synchronize access to s0.
+    std::recursive_mutex _lock; // To synchronize access to s0.
   };
 
 } // namespace atn
diff --git a/runtime/Cpp/runtime/dfa/LexerDFASerializer.cpp b/runtime/Cpp/runtime/dfa/LexerDFASerializer.cpp
index 48a0f3e28..e68dcf36b 100755
--- a/runtime/Cpp/runtime/dfa/LexerDFASerializer.cpp
+++ b/runtime/Cpp/runtime/dfa/LexerDFASerializer.cpp
@@ -29,11 +29,13 @@
  *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include "VocabularyImpl.h"
+
 #include "LexerDFASerializer.h"
 
 using namespace org::antlr::v4::runtime::dfa;
 
-LexerDFASerializer::LexerDFASerializer(DFA *dfa) : DFASerializer(dfa, lexerTokenNames_) {
+LexerDFASerializer::LexerDFASerializer(DFA *dfa) : DFASerializer(dfa, VocabularyImpl::EMPTY_VOCABULARY) {
 }
 
 std::wstring LexerDFASerializer::getEdgeLabel(size_t i) const {
diff --git a/runtime/Cpp/runtime/dfa/LexerDFASerializer.h b/runtime/Cpp/runtime/dfa/LexerDFASerializer.h
index b975c126a..bb392cdb9 100755
--- a/runtime/Cpp/runtime/dfa/LexerDFASerializer.h
+++ b/runtime/Cpp/runtime/dfa/LexerDFASerializer.h
@@ -44,7 +44,6 @@ namespace dfa {
     LexerDFASerializer(DFA *dfa);
 
   protected:
-    std::vector<std::wstring> lexerTokenNames_;
     virtual std::wstring getEdgeLabel(size_t i) const override;
   };