diff --git a/src/secp256k1/src/tests.c b/src/secp256k1/src/tests.c
--- a/src/secp256k1/src/tests.c
+++ b/src/secp256k1/src/tests.c
@@ -4440,7 +4440,7 @@
         }
     } else {
         FILE *frand = fopen("/dev/urandom", "r");
-        if ((frand == NULL) || !fread(&seed16, sizeof(seed16), 1, frand)) {
+        if ((frand == NULL) || fread(&seed16, sizeof(seed16), 1, frand) != sizeof(seed16)) {
             uint64_t t = time(NULL) * (uint64_t)1337;
             seed16[0] ^= t;
             seed16[1] ^= t >> 8;