Minor fix to make sure strings are produced.

basis/ui/gestures/gestures.factor

@@ -326,10 +326,10 @@ M: macosx modifiers>string
             { S+ [ "\u0021e7" ] }
             { C+ [ "\u002303" ] }
         } case
-    ] map concat ;
+    ] map "" concat-as ;
 
 M: object modifiers>string
-    [ name>> ] map concat ;
+    [ name>> ] map "" concat-as ;
 
 HOOK: keysym>string os ( keysym -- string )
 

basis/xml/writer/writer.factor

@@ -19,7 +19,7 @@ SYMBOL: indentation
 
 : indent-string ( -- string )
     xml-pprint? get
-    [ indentation get indenter get <repetition> concat ]
+    [ indentation get indenter get <repetition> "" concat-as ]
     [ "" ] if ;
 
 : ?indent ( -- )