diff --git a/extra/strings/lib/lib.factor b/extra/strings/lib/lib.factor
index 6affe067fd..7f13cd58a9 100644
--- a/extra/strings/lib/lib.factor
+++ b/extra/strings/lib/lib.factor
@@ -1,4 +1,4 @@
-USING: math arrays sequences kernel random splitting strings ;
+USING: math arrays sequences kernel random splitting strings unicode.case ;
 IN: strings.lib
 
 : char>digit ( c -- i ) 48 - ;