diff --git a/src/vim9script.c b/src/vim9script.c
index 7d783ea..2e94b8e 100644
--- a/src/vim9script.c
+++ b/src/vim9script.c
@@ -64,16 +64,17 @@
     int
 not_in_vim9(exarg_T *eap)
 {
-    switch (eap->cmdidx)
-    {
-	case CMD_insert:
-	case CMD_append:
-	case CMD_change:
-	case CMD_xit:
-	    semsg(_("E1100: Missing :let: %s"), eap->cmd);
-	    return FAIL;
-	default: break;
-    }
+    if (in_vim9script())
+	switch (eap->cmdidx)
+	{
+	    case CMD_insert:
+	    case CMD_append:
+	    case CMD_change:
+	    case CMD_xit:
+		semsg(_("E1100: Missing :let: %s"), eap->cmd);
+		return FAIL;
+	    default: break;
+	}
     return OK;
 }