diff --git a/compiler-rt/lib/ubsan/ubsan_diag.h b/compiler-rt/lib/ubsan/ubsan_diag.h
index c836647c98f3c..d37bc309fdd0a 100644
--- a/compiler-rt/lib/ubsan/ubsan_diag.h
+++ b/compiler-rt/lib/ubsan/ubsan_diag.h
@@ -37,10 +37,11 @@ class Location {
 
 private:
   LocationKind Kind;
-  // FIXME: In C++11, wrap these in an anonymous union.
-  SourceLocation SourceLoc;
-  MemoryLocation MemoryLoc;
-  const SymbolizedStack *SymbolizedLoc;  // Not owned.
+  union {
+    SourceLocation SourceLoc;
+    MemoryLocation MemoryLoc;
+    const SymbolizedStack *SymbolizedLoc; // Not owned.
+  };
 
 public:
   Location() : Kind(LK_Null) {}