diff --git a/src/prolog/toplevel.pl b/src/prolog/toplevel.pl
index 27bf71f5..a3c3f1af 100644
--- a/src/prolog/toplevel.pl
+++ b/src/prolog/toplevel.pl
@@ -65,6 +65,7 @@
 	      false),
     (  EqPrec < FPrec -> true
     ;  '$quoted_token'(F) -> true
+    ;  atom_length(F, 1), '$graphic_token_char'(F) -> true
     ;  EqPrec == FPrec,
        memberchk(EqSpec, [fx,xfx,yfx])
     ).