diff --git a/grammar/src/class_members.grm b/grammar/src/class_members.grm
index a89d3128caf..af972588c7d 100644
--- a/grammar/src/class_members.grm
+++ b/grammar/src/class_members.grm
@@ -42,7 +42,7 @@ anonymousInitializer
   ;
 
 companionObject
-  : modifiers "companion" "object"
+  : modifiers "companion" "object" SimpleName (":" delegationSpecifier{","})? classBody?
   ;
 
 valueParameters