diff --git a/tools/recorder2timeline.cpp b/tools/recorder2timeline.cpp
index 5546f37..df24748 100644
--- a/tools/recorder2timeline.cpp
+++ b/tools/recorder2timeline.cpp
@@ -32,6 +32,8 @@ static const char* type_name(int type) {
             return "HDF5";
         case RECORDER_FTRACE:
             return "USER";
+        default:
+            return "UNKNOWN";
     }
 }