diff --git a/repos/gems/run/sculpt_image.run b/repos/gems/run/sculpt_image.run
index 0373664ff0..70fc016e0a 100644
--- a/repos/gems/run/sculpt_image.run
+++ b/repos/gems/run/sculpt_image.run
@@ -23,7 +23,7 @@ proc assert_include { include } {
 proc assert_run_arg { arg_name } {
 	global argv
 	if {[lsearch $argv $arg_name] == -1} {
-		puts stderr "missing run-tool argument: $arg"
+		puts stderr "missing run-tool argument: $arg_name"
 		exit 1
 	}
 }