Fix final test for invalid base64url chars

* src/fns.c (base64_decode_1): Fix test for invalid base64url
(bug#45562).  Noted by Andreas Schwab.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/fns.c b/src/fns.c
index a1782166228..7b9e3b0f7fc 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -3955,7 +3955,7 @@ base64_decode_1 (const char *from, char *to, ptrdiff_t length,
       if (c == '=')
         continue;
 
-      if (v1 < 0)
+      if (v1 == 0)
         return -1;
       value += v1 - 1;