diff --git a/src/errors.h b/src/errors.h
index e302ecc..6f275fa 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -3246,4 +3246,6 @@
 	INIT(= N_("E1268: Cannot use s: in Vim9 script: %s"));
 EXTERN char e_cannot_create_vim9_script_variable_in_function_str[]
 	INIT(= N_("E1269: Cannot create a Vim9 script variable in a function: %s"));
+EXTERN char e_cannot_use_s_backslash_in_vim9_script[]
+	INIT(= N_("E1270: Cannot use :s\\/sub/ in Vim9 script"));
 #endif