diff --git a/thun/gnu-prolog/parser.pl b/thun/gnu-prolog/parser.pl
index b0e4be4..cd8a35c 100644
--- a/thun/gnu-prolog/parser.pl
+++ b/thun/gnu-prolog/parser.pl
@@ -30,8 +30,7 @@ joy_term(N) --> num(N), !.
 joy_term(J) --> "[", !, joy_parse(J), "]".
 joy_term(C) --> symbol(C).
 
-symbol(C) --> chars(Chars), !, {Chars \= [61, 61], atom_codes(C, Chars)}.
-
+symbol(C) --> chars(Chars), !, {Chars \= "==", atom_codes(C, Chars)}.
 
 
 % Line is the next new-line delimited line from standard input stream as
@@ -69,4 +68,3 @@ digits([]) --> [].
 
 digit(C) --> [C], { nonvar(C), C =< 57, C >= 48 }.
 
-