diff --git a/llvm/lib/BinaryFormat/MsgPackDocument.cpp b/llvm/lib/BinaryFormat/MsgPackDocument.cpp
index 53720c542e14d8..81ea4cee1a9d13 100644
--- a/llvm/lib/BinaryFormat/MsgPackDocument.cpp
+++ b/llvm/lib/BinaryFormat/MsgPackDocument.cpp
@@ -277,6 +277,8 @@ void Document::writeToBlob(std::string &Blob) {
     case Type::String:
       MPWriter.write(Node.getString());
       break;
+    case Type::Empty:
+      llvm_unreachable("unhandled empty msgpack node");
     default:
       llvm_unreachable("unhandled msgpack object kind");
     }
@@ -310,4 +312,3 @@ void Document::writeToBlob(std::string &Blob) {
     }
   }
 }
-