diff --git a/lib/Bitcode/Reader/Deserialize.cpp b/lib/Bitcode/Reader/Deserialize.cpp
index febb2d7..d1d6ef0 100644
--- a/lib/Bitcode/Reader/Deserialize.cpp
+++ b/lib/Bitcode/Reader/Deserialize.cpp
@@ -103,6 +103,11 @@
 void Deserializer::ReadPtr(void*& PtrRef) {
   unsigned PtrId = ReadInt();
   
+  if (PtrId == 0) {
+    PtrRef = NULL;
+    return;
+  }  
+  
   BPatchEntry& E = BPatchMap[PtrId];
   
   if (E.Ptr == NULL) {
diff --git a/lib/Bitcode/Writer/Serialize.cpp b/lib/Bitcode/Writer/Serialize.cpp
index fbe1d10..a1d7320 100644
--- a/lib/Bitcode/Writer/Serialize.cpp
+++ b/lib/Bitcode/Writer/Serialize.cpp
@@ -58,10 +58,13 @@
 }
 
 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;
   }