diff --git a/ghc/compiler/parser/hsparser.y b/ghc/compiler/parser/hsparser.y
index 627ccfe5a51d4c4c852dfb8059d8ec2dc9b10b2c..663777977cc5bb4b83f56d6557b81922c8212f08 100644
--- a/ghc/compiler/parser/hsparser.y
+++ b/ghc/compiler/parser/hsparser.y
@@ -511,7 +511,7 @@ classd	:  classkey btype DARROW simple_con_app1 cbody
 	|  classkey btype cbody
 		/* We have to say btype rather than simple_con_app1, else
 		   we get reduce/reduce errs */
-		{ check_class_decl_head($3);
+		{ check_class_decl_head($2);
 		  $$ = mkcbind(Lnil,$2,$3,startlineno); }
 	;