diff --git a/Makefile b/Makefile
index 149fd1025..3b47b4d53 100644
--- a/Makefile
+++ b/Makefile
@@ -125,7 +125,7 @@ clean:
 	[ "${FLOCKER}" != "$0" ] && exec env FLOCKER="$0" flock -en .stack-work.lock "$0" "$@" || :
 
 .develop.env:
-	[[ ! -z "$(CI)" || ! -z "$$PORT_OFFSET" ]] || ( echo "Not in develop!" 2>&1 ; exit 1 )
+	[ ! -z "$(CI)" -o ! -z "$$PORT_OFFSET" ] || ( echo "Not in develop!" 2>&1 ; exit 1 )
 
 # .PHONY: --stack-work-%
 # --stack-work-%: .stack-work.lock