diff --git a/t/picotls.c b/t/picotls.c
index 5390a66..01fb2e3 100644
--- a/t/picotls.c
+++ b/t/picotls.c
@@ -53,7 +53,7 @@
 
     {
         static const uint8_t input[] = {};
-        ok(select_cipher(&selected, candidates, input, input + sizeof(input), 0) == PTLS_ALERT_HANDSHAKE_FAILURE);
+        ok(select_cipher(&selected, candidates, input, input, 0) == PTLS_ALERT_HANDSHAKE_FAILURE);
     }
 
     {