diff --git a/pam_yubico.c b/pam_yubico.c
index 9766afc..19ce8c6 100644
--- a/pam_yubico.c
+++ b/pam_yubico.c
@@ -628,6 +628,7 @@ do_challenge_response(pam_handle_t *pamh, struct cfg *cfg, const char *username)
 
   DBG(("Challenge-response success!"));
   errstr = NULL;
+  errno = 0;
 
  out:
   if (yk_errno) {