diff --git a/lib/ExecutionEngine/JIT/JIT.cpp b/lib/ExecutionEngine/JIT/JIT.cpp
index 383b380..413308c 100644
--- a/lib/ExecutionEngine/JIT/JIT.cpp
+++ b/lib/ExecutionEngine/JIT/JIT.cpp
@@ -489,6 +489,8 @@
   if (void *Addr = getPointerToGlobalIfAvailable(F))
     return Addr;   // Check if function already code gen'd
 
+  MutexGuard locked(lock);
+
   // Make sure we read in the function if it exists in this Module.
   if (F->hasNotBeenReadFromBitcode()) {
     // Determine the module provider this function is provided by.
@@ -509,13 +511,11 @@
       abort();
     }
   }
-  
+
   if (void *Addr = getPointerToGlobalIfAvailable(F)) {
     return Addr;
   }
 
-  MutexGuard locked(lock);
-  
   if (F->isDeclaration()) {
     void *Addr = getPointerToNamedFunction(F->getName());
     addGlobalMapping(F, Addr);