diff --git a/src/bench_internal.c b/src/bench_internal.c
index 2224058f64..e7600877fc 100644
--- a/src/bench_internal.c
+++ b/src/bench_internal.c
@@ -110,10 +110,11 @@ void bench_scalar_mul(void* arg, int iters) {
 void bench_scalar_split(void* arg, int iters) {
     int i, j = 0;
     bench_inv *data = (bench_inv*)arg;
+    secp256k1_scalar tmp;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_scalar_split_lambda(&data->scalar[0], &data->scalar[1], &data->scalar[0]);
-        j += secp256k1_scalar_add(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
+        secp256k1_scalar_split_lambda(&tmp, &data->scalar[1], &data->scalar[0]);
+        j += secp256k1_scalar_add(&data->scalar[0], &tmp, &data->scalar[1]);
     }
     CHECK(j <= iters);
 }