diff --git a/src/errors.h b/src/errors.h
index 6346bf2..3c76bb7 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -355,8 +355,7 @@
 	INIT(= N_("E1084: Cannot delete Vim9 script function %s"));
 EXTERN char e_not_callable_type_str[]
 	INIT(= N_("E1085: Not a callable type: %s"));
-EXTERN char e_cannot_use_function_inside_def[]
-	INIT(= N_("E1086: Cannot use :function inside :def"));
+// E1086 unused
 EXTERN char e_cannot_use_index_when_declaring_variable[]
 	INIT(= N_("E1087: Cannot use an index when declaring a variable"));
 // E1088 unused