diff --git a/src/scripting/lua/core.c b/src/scripting/lua/core.c
index f10f460d..3f206c1d 100644
--- a/src/scripting/lua/core.c
+++ b/src/scripting/lua/core.c
@@ -790,7 +790,7 @@ finish_lua(void)
 /* Error reporting. */
 
 void
-alert_lua_error(char *msg)
+alert_lua_error(const char *msg)
 {
 	if (errterm) {
 		info_box(errterm, MSGBOX_NO_TEXT_INTL | MSGBOX_FREE_TEXT,
@@ -804,7 +804,7 @@ alert_lua_error(char *msg)
 }
 
 void
-alert_lua_error2(char *msg, char *msg2)
+alert_lua_error2(const char *msg, char *msg2)
 {
 	char *tmp = stracpy(msg);
 
diff --git a/src/scripting/lua/core.h b/src/scripting/lua/core.h
index 2f2773b6..815a9acb 100644
--- a/src/scripting/lua/core.h
+++ b/src/scripting/lua/core.h
@@ -22,8 +22,8 @@ extern lua_State *lua_state;
 int prepare_lua(struct session *);
 void finish_lua(void);
 
-void alert_lua_error(char *);
-void alert_lua_error2(char *, char *);
+void alert_lua_error(const char *);
+void alert_lua_error2(const char *, char *);
 
 enum evhook_status dialog_lua_console(va_list ap, void *data);
 enum evhook_status free_lua_console_history(va_list ap, void *data);