diff --git a/src/vim9expr.c b/src/vim9expr.c
index 83c68a9..edaee50 100644
--- a/src/vim9expr.c
+++ b/src/vim9expr.c
@@ -1233,7 +1233,7 @@
     len = get_env_len(arg);
     if (len == 0)
     {
-	semsg(_(e_syntax_error_at_str), start - 1);
+	semsg(_(e_syntax_error_at_str), start);
 	return FAIL;
     }