diff --git a/fractal_server/app/runner/_slurm/executor.py b/fractal_server/app/runner/_slurm/executor.py
index 2d2587e369..bacad87c79 100644
--- a/fractal_server/app/runner/_slurm/executor.py
+++ b/fractal_server/app/runner/_slurm/executor.py
@@ -222,7 +222,7 @@ def compose_sbatch_script(
 
         cmd = [
             shlex.join(["srun", *cmdline]),
-            f"chmod 777 {outpath.parent / '*'}",
+            f"chmod -f 777 {outpath.parent / '*'}",
         ]
 
         script_lines = ["#!/bin/sh"] + sbatch_lines + non_sbatch_lines + cmd