diff --git a/lib/VMCore/Metadata.cpp b/lib/VMCore/Metadata.cpp
index 8e025b6d7a2..1163b4709ce 100644
--- a/lib/VMCore/Metadata.cpp
+++ b/lib/VMCore/Metadata.cpp
@@ -115,7 +115,11 @@ void MDNode::dropAllReferences() {
 }
 
 MDNode::~MDNode() {
-  getType()->getContext().pImpl->MDNodeSet.RemoveNode(this);
+  {
+    LLVMContextImpl *pImpl = getType()->getContext().pImpl;
+    sys::SmartScopedWriter<true> Writer(pImpl->ConstantsLock);
+    pImpl->MDNodeSet.RemoveNode(this);
+  }
   dropAllReferences();
 }