diff --git a/main/editline/Makefile.in b/main/editline/Makefile.in
index f17cfd43a7..47fbb8d09e 100644
--- a/main/editline/Makefile.in
+++ b/main/editline/Makefile.in
@@ -4,7 +4,7 @@
 
 OSTYPE=$(shell uname -s)
 define cyg_subst_sys
-	if uname -s | grep -qi cygwin; then \
+	if uname -s | ${GREP} -qi cygwin; then \
 	cat $@ | sed -e s/"sys\.h"/"config.h"/g > $@.copy; \
 	mv --force $@.copy $@; \
 	fi