diff --git a/src/secp256k1/src/tests_exhaustive.c b/src/secp256k1/src/tests_exhaustive.c
--- a/src/secp256k1/src/tests_exhaustive.c
+++ b/src/secp256k1/src/tests_exhaustive.c
@@ -353,6 +353,14 @@
     unsigned char rand32[32];
     secp256k1_context *ctx;
 
+    /* Disable buffering for stdout to improve reliability of getting
+     * diagnostic information. Happens right at the start of main because
+     * setbuf must be used before any other operation on the stream. */
+    setbuf(stdout, NULL);
+    /* Also disable buffering for stderr because it's not guaranteed that it's
+     * unbuffered on all systems. */
+    setbuf(stderr, NULL);
+
     printf("Exhaustive tests for order %lu\n", (unsigned long)EXHAUSTIVE_TEST_ORDER);
 
     /* find iteration count */