-extern bool ecdsa_sign(ecdsa_t *ecdsa, const void *in, size_t inlen, void *out);
-extern bool ecdsa_verify(ecdsa_t *ecdsa, const void *in, size_t inlen, const void *out);
+extern bool ecdsa_sign(ecdsa_t *ecdsa, const void *in, size_t inlen, void *out) __attribute__((__warn_unused_result__));
+extern bool ecdsa_verify(ecdsa_t *ecdsa, const void *in, size_t inlen, const void *out) __attribute__((__warn_unused_result__));