diff --git a/src/rntviewer.cpp b/src/rntviewer.cpp
index 5ab203f..9803068 100644
--- a/src/rntviewer.cpp
+++ b/src/rntviewer.cpp
@@ -136,7 +136,9 @@ int main(int argc, char **argv)
   app.ntpl_name = args.ntpl_name; // may be null
   app.base_display_addr = args.start_addr;
   b8 success = get_tfile_data(arena, app.inspected_file, app.ntpl_name, app.tfile_data);
-  if (success)
+  if (!app.ntpl_name.str)
+    fprintf(stderr, "Warning: found no RNTuples in %s\n", args.file_name.c());
+  else if (success)
     app.rndata = get_rntuple_data(arena, app.inspected_file, app.ntpl_name, args.extended_info);
 
   if (args.print_to_terminal) {