diff --git a/tests/renderer/utils.py b/tests/renderer/utils.py
index c422e8415347e630a623832f7b7d4081c8104032..9717af0b81fb83eed279793470977f6a3b10c7ec 100644
--- a/tests/renderer/utils.py
+++ b/tests/renderer/utils.py
@@ -242,7 +242,7 @@ def run_renderer(
     cmd[0] += binary_suffix
 
     if in_meta_files is not None:
-        cmd[5:5] = ["-im", *in_meta_files]
+        cmd.extend(["-im", *in_meta_files])
 
     if trj_file is not None:
         cmd.extend(["-T", str(trj_file)])