diff --git a/src/eval.c b/src/eval.c
index 4d94d67..6537ffe 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -5376,6 +5376,8 @@
 	}
 	return &pos;
     }
+    if (in_vim9script())
+	semsg(_(e_invalid_value_for_line_number_str), name);
     return NULL;
 }