diff --git a/src/bench_schnorrsig.c b/src/bench_schnorrsig.c
index 7b4b4b44a..d95bc00f4 100644
--- a/src/bench_schnorrsig.c
+++ b/src/bench_schnorrsig.c
@@ -28,13 +28,13 @@ typedef struct {
 void bench_schnorrsig_sign(void* arg, int iters) {
     bench_schnorrsig_data *data = (bench_schnorrsig_data *)arg;
     int i;
-    unsigned char msg[MSGLEN] = "benchmarkexamplemessagetemplate";
+    unsigned char msg[MSGLEN] = {0};
     unsigned char sig[64];
 
     for (i = 0; i < iters; i++) {
         msg[0] = i;
         msg[1] = i >> 8;
-        CHECK(secp256k1_schnorrsig_sign(data->ctx, sig, msg, data->keypairs[i], NULL));
+        CHECK(secp256k1_schnorrsig_sign_custom(data->ctx, sig, msg, MSGLEN, data->keypairs[i], NULL));
     }
 }
 
@@ -60,6 +60,7 @@ int main(void) {
     data.msgs = (const unsigned char **)malloc(iters * sizeof(unsigned char *));
     data.sigs = (const unsigned char **)malloc(iters * sizeof(unsigned char *));
 
+    CHECK(MSGLEN >= 4);
     for (i = 0; i < iters; i++) {
         unsigned char sk[32];
         unsigned char *msg = (unsigned char *)malloc(MSGLEN);
@@ -71,7 +72,7 @@ int main(void) {
         msg[1] = sk[1] = i >> 8;
         msg[2] = sk[2] = i >> 16;
         msg[3] = sk[3] = i >> 24;
-        memset(&msg[4], 'm', 28);
+        memset(&msg[4], 'm', MSGLEN - 4);
         memset(&sk[4], 's', 28);
 
         data.keypairs[i] = keypair;
@@ -80,7 +81,7 @@ int main(void) {
         data.sigs[i] = sig;
 
         CHECK(secp256k1_keypair_create(data.ctx, keypair, sk));
-        CHECK(secp256k1_schnorrsig_sign(data.ctx, sig, msg, keypair, NULL));
+        CHECK(secp256k1_schnorrsig_sign_custom(data.ctx, sig, msg, MSGLEN, keypair, NULL));
         CHECK(secp256k1_keypair_xonly_pub(data.ctx, &pk, NULL, keypair));
         CHECK(secp256k1_xonly_pubkey_serialize(data.ctx, pk_char, &pk) == 1);
     }