diff -r ba88bb44c192 -r 9b00f09f7721 src/Pure/ML/ml_lex.ML
--- a/src/Pure/ML/ml_lex.ML	Sat Jul 23 16:12:12 2011 +0200
+++ b/src/Pure/ML/ml_lex.ML	Sat Jul 23 16:37:17 2011 +0200
@@ -136,7 +136,7 @@
 
 open Basic_Symbol_Pos;
 
-fun !!! msg = Symbol_Pos.!!! ("SML lexical error: " ^ msg);
+fun !!! msg = Symbol_Pos.!!! (fn () => "SML lexical error: " ^ msg);
 
 
 (* blanks *)