diff --git a/Makefile b/Makefile
index 2c49549..c109694 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,11 @@ frfac:
 check:
 	`./latest_perl` -wc frfac.in
 	perlcritic frfac.in
-	ksh93 -n getviaphone
+	if which ksh93 2> /dev/null; then \
+		ksh93 -n getviaphone; \
+	else \
+		ksh -n getviaphone; \
+        fi
 
 install: frfac
 	sudo install -o root -g wheel -m 0755 -d /usr/local/bin