diff --git a/test/default/sign.c b/test/default/sign.c
index 3bcde4d4..06c77d96 100644
--- a/test/default/sign.c
+++ b/test/default/sign.c
@@ -1115,6 +1115,18 @@ int main(void)
     printf("%u tests\n", i);
 
     i--;
+
+    memcpy(sm, test_data[i].m, i);
+    if (crypto_sign(sm, &smlen, sm, i, skpk) != 0) {
+        printf("crypto_sign() with overlap failed\n");
+    }
+    if (crypto_sign_open(sm, &mlen, sm, smlen, test_data[i].pk) != 0) {
+        printf("crypto_sign_open() with overlap failed\n");
+    }
+    if (memcmp(test_data[i].m, sm, (size_t)mlen) != 0) {
+        printf("crypto_sign_open() with overlap failed (content)\n");
+    }
+
     for (j = 1U; j < 8U; j++) {
         sig[63] ^= (j << 5);
         if (crypto_sign_verify_detached(sig,