diff --git a/scripts/generate_bash_completion.sh b/scripts/generate_bash_completion.sh
index 778810570c..46a3965f85 100755
--- a/scripts/generate_bash_completion.sh
+++ b/scripts/generate_bash_completion.sh
@@ -34,7 +34,7 @@ die() {
 }
 
 get_optarg() {
-  expr -- "${1}" : "[^=]*=\\(.*\\)"
+  expr "${1}" : "[^=]*=\\(.*\\)"
 }
 
 append=