1 files changed, 4 insertions, 1 deletions
diff --git a/lib/Bitcode/Writer/Serialize.cpp b/lib/Bitcode/Writer/Serialize.cpp
index fbe1d1007c..a1d732047a 100644
--- a/lib/Bitcode/Writer/Serialize.cpp
+++ b/lib/Bitcode/Writer/Serialize.cpp
@@ -58,10 +58,13 @@ void Serializer::EmitCStr(const char* s) {
 }
 
 unsigned Serializer::getPtrId(void* ptr) {
+  if (!ptr)
+    return 0;
+  
   MapTy::iterator I = PtrMap.find(ptr);
   
   if (I == PtrMap.end()) {
-    unsigned id = PtrMap.size();
+    unsigned id = PtrMap.size()+1;
     PtrMap[ptr] = id;
     return id;
   }