diff --git a/test/default/sign.c b/test/default/sign.c
index 06c77d96..99ed085b 100644
--- a/test/default/sign.c
+++ b/test/default/sign.c
@@ -1059,6 +1059,7 @@ int main(void)
     unsigned int i;
     unsigned int j;
 
+    memset(sig, 0, sizeof sig);
     for (i = 0U; i < (sizeof test_data) / (sizeof test_data[0]); i++) {
         memcpy(skpk, test_data[i].sk, crypto_sign_SEEDBYTES);
         memcpy(skpk + crypto_sign_SEEDBYTES, test_data[i].pk,