diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
index 0c48ac498ec84..15c3e241fce7a 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
@@ -1257,7 +1257,7 @@ Status ScriptInterpreterPythonImpl::SetBreakpointCommandCallbackFunction(
     oneliner += "(frame, bp_loc, internal_dict)";
   } else {
     error.SetErrorStringWithFormat("expected 3 or 4 argument "
-                                   "function, %s has %d",
+                                   "function, %s has %zu",
                                    function_name, num_args);
     return error;
   }