diff --git a/cf/sunos.m4 b/cf/sunos.m4
index 641381ee2..53ad31be0 100644
--- a/cf/sunos.m4
+++ b/cf/sunos.m4
@@ -11,7 +11,7 @@ case "$host" in
 *-*-solaris2.7)
 	sunos=57
 	;;
-*-*-solaris2.[89])
+*-*-solaris2.[[89]])
 	sunos=58
 	;;
 *-*-solaris2*)