diff --git a/vm/alloc/Alloc.cpp b/vm/alloc/Alloc.cpp
index 7755f11..b37b9e1 100644
--- a/vm/alloc/Alloc.cpp
+++ b/vm/alloc/Alloc.cpp
@@ -350,7 +350,10 @@
 
 bool dvmIsHeapAddress(void *address)
 {
-    return dvmHeapSourceContainsAddress(address);
+    dvmLockHeap();
+    bool result = dvmHeapSourceContainsAddress(address);
+    dvmUnlockHeap();
+    return result;
 }
 
 bool dvmIsNonMovingObject(const Object* object)