diff --git a/glslang/MachineIndependent/linkValidate.cpp b/glslang/MachineIndependent/linkValidate.cpp
index 9b45570e..7fed096b 100644
--- a/glslang/MachineIndependent/linkValidate.cpp
+++ b/glslang/MachineIndependent/linkValidate.cpp
@@ -642,7 +642,7 @@ void TIntermediate::mergeBlockDefinitions(TInfoSink& infoSink, TIntermSymbol* bl
         }
         TMergeBlockTraverser(const TIntermSymbol* newSym, const glslang::TType* unitType, glslang::TIntermediate* unit,
                              const std::map<unsigned int, unsigned int>* memberIdxUpdates)
-            : newSymbol(newSym), unitType(unitType), unit(unit), memberIndexUpdates(memberIdxUpdates)
+            : TIntermTraverser(false, true), newSymbol(newSym), unitType(unitType), unit(unit), memberIndexUpdates(memberIdxUpdates)
         {
         }
         virtual ~TMergeBlockTraverser() {}