diff --git a/configure.ac b/configure.ac
index 726b888adf..b42e7643ce 100644
--- a/configure.ac
+++ b/configure.ac
@@ -564,12 +564,13 @@ AC_MSG_NOTICE(checking for new missing prototypes)
 
 AC_DEFUN([CHECK_PROTO], [
 	AC_EGREP_HEADER([[^A-Za-z0-9_]$1([ 	]+[A-Za-z0-9_]*)?[	 ]*\(],
-	$2,
-	,
+	[$2],
+	[],
 	[
 		AC_MSG_NOTICE([adding prototype for $1])
-		AC_DEFINE(patsubst([NEED_PROTO_NAME], [NAME], translit([$1], [[a-z]], [[A-Z]])))
-	])])
+		AC_DEFINE(AS_TR_CPP([NEED_PROTO_$1]))
+	])
+])
 
 if test "$have_remove" = yes ; then
 	CHECK_PROTO(remove, stdio.h)