diff --git a/src/machine.cpp b/src/machine.cpp
index dce3bfe185..84a34caf67 100644
--- a/src/machine.cpp
+++ b/src/machine.cpp
@@ -3010,7 +3010,7 @@ Machine::Machine(System* system, Heap* heap, Finder* bootFinder,
 
   const char* bootstrapProperty = findProperty(this, BOOTSTRAP_PROPERTY);
   const char* bootstrapPropertyDup = bootstrapProperty ? strdup(bootstrapProperty) : 0;
-  const char* bootstrapPropertyEnd = bootstrapProperty + (bootstrapProperty ? strlen(bootstrapProperty) : 0);
+  const char* bootstrapPropertyEnd = bootstrapPropertyDup + (bootstrapPropertyDup ? strlen(bootstrapPropertyDup) : 0);
   char* codeLibraryName = (char*)bootstrapPropertyDup;
   char* codeLibraryNameEnd = 0;
   if (codeLibraryName && (codeLibraryNameEnd = strchr(codeLibraryName, system->pathSeparator())))