--- freetype-config
+++ freetype-config
@@ -48,7 +48,7 @@
 while test $# -gt 0 ; do
   case "$1" in
   -*=*)
-    optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'`
+    optarg=`echo "$1" | sed 's/[-_[:alnum:]]*=//'`
     ;;
   *)
     optarg=