diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3157,7 +3157,7 @@
     return 160;
   if (Left.is(TT_CastRParen))
     return 100;
-  if (Left.isOneOf(tok::kw_class, tok::kw_struct))
+  if (Left.isOneOf(tok::kw_class, tok::kw_struct, tok::kw_union))
     return 5000;
   if (Left.is(tok::comment))
     return 1000;