diff --git a/build/mkdep b/build/mkdep
index 006f05abbc..080ac435a7 100755
--- a/build/mkdep
+++ b/build/mkdep
@@ -25,7 +25,7 @@ set -e				# exit immediately if any errors occur
 
 MAKE=Makefile			# default makefile name is "Makefile"
 NOSLASH="no"			# by default, / dependencies are included
-CC=cc				# default compiler is cc
+CC=${CC-cc}				# default compiler is cc
 
 while :
 	do case "$1" in
@@ -58,7 +58,7 @@ while :
 done
 
 if [ $# = 0 ] ; then
-	echo 'usage: mkdep [-p] [-f makefile] [flags] file ...'
+	echo 'usage: mkdep [-p] [-s] [-c cc] [-f makefile] [flags] file ...'
 	exit 1
 fi