diff --git a/hphp/runtime/vm/translator/hopt/vectortranslator.cpp b/hphp/runtime/vm/translator/hopt/vectortranslator.cpp
index 46459870b..cf4a3236d 100644
--- a/hphp/runtime/vm/translator/hopt/vectortranslator.cpp
+++ b/hphp/runtime/vm/translator/hopt/vectortranslator.cpp
@@ -600,8 +600,7 @@ static inline TypedValue* baseGImpl(TypedValue *key,
       varEnv->set(name, &tv);
       base = varEnv->lookup(name);
     } else {
-      tvWriteNull(&mis->tvScratch);
-      base = &mis->tvScratch;
+      return const_cast<TypedValue*>(init_null_variant.asTypedValue());
     }
   }
   decRefStr(name);
diff --git a/hphp/test/vm/unset_undef_g.php b/hphp/test/vm/unset_undef_g.php
new file mode 100644
index 000000000..3a1e6c52d
--- /dev/null
+++ b/hphp/test/vm/unset_undef_g.php
@@ -0,0 +1,5 @@
+<?php
+function test($t) {
+  unset($GLOBALS['foo']['bar']);
+}
+test(null);
diff --git a/hphp/test/vm/unset_undef_g.php.exp b/hphp/test/vm/unset_undef_g.php.exp
new file mode 100644
index 000000000..e69de29bb