diff --git a/src/mp/util.cpp b/src/mp/util.cpp
index 107985e5..7126df9a 100644
--- a/src/mp/util.cpp
+++ b/src/mp/util.cpp
@@ -71,7 +71,7 @@ std::string ThreadName(const char* exe_name)
     buffer << std::this_thread::get_id();
 #endif
 
-    return std::move(buffer.str());
+    return std::move(buffer).str();
 }
 
 std::string LogEscape(const kj::StringTree& string)