diff -r 79b733010bc5 -r 2b6ba4d4e19a Nominal-General/nominal_permeq.ML
--- a/Nominal-General/nominal_permeq.ML	Thu May 06 13:25:37 2010 +0200
+++ b/Nominal-General/nominal_permeq.ML	Thu May 06 14:09:21 2010 +0200
@@ -117,7 +117,7 @@
     let
       val hd = head_of trm
     in 
-      if is_Const hd andalso (fst (dest_Const hd)) mem bad_hds then ()
+      if is_Const hd andalso member (op =) bad_hds (fst (dest_Const hd)) then ()
       else (if strict_flag then error else warning) 
              ("Cannot solve equivariance for " ^ (Syntax.string_of_term ctxt trm))
     end
@@ -183,4 +183,4 @@
 fun perm_strict_simp_meth (thms, consts) ctxt = 
   SIMPLE_METHOD (HEADGOAL (eqvt_strict_tac ctxt thms consts))
 
-end; (* structure *)
\ No newline at end of file
+end; (* structure *)