diff --git a/patch-control.sh b/patch-control.sh
index ba4878db1d5f0b1d93c4e2cf144965a66ae778ea..a378e8acfa501199450923e2f0681c83e45fda00 100644
--- a/patch-control.sh
+++ b/patch-control.sh
@@ -167,7 +167,7 @@ zenity --question \
        --cancel-label="No, thanks" && firefox http://localhost:1301/ &
 
 # Wait the end of the run
-let 'run_duration_seconds = ${run_duration} * 60'
+let "run_duration_seconds = ${run_duration} * 60"
 sleep ${run_duration_seconds}
 
 log "Run ${run_number} finished."