diff --git a/llvm/include/llvm/Support/YAMLTraits.h b/llvm/include/llvm/Support/YAMLTraits.h
index a8319a6c10d5..98964fc00200 100644
--- a/llvm/include/llvm/Support/YAMLTraits.h
+++ b/llvm/include/llvm/Support/YAMLTraits.h
@@ -1069,6 +1069,7 @@ operator<<(Output &yout, T &seq) {
           seq.resize(index+1);                                              \
         return seq[index];                                                  \
       }                                                                     \
+      static const bool flow = true;                                        \
     };                                                                      \
   }                                                                         \
   }