diff --git a/library/ecp_invasive.h b/library/ecp_invasive.h
index 744945c..cfa12e9 100644
--- a/library/ecp_invasive.h
+++ b/library/ecp_invasive.h
@@ -190,7 +190,7 @@
 #if defined(MBEDTLS_ECP_DP_SECP256K1_ENABLED)
 
 MBEDTLS_STATIC_TESTABLE
-int mbedtls_ecp_mod_p256k1(mbedtls_mpi *N);
+int mbedtls_ecp_mod_p256k1_raw(mbedtls_mpi_uint *X, size_t X_limbs);
 
 #endif /* MBEDTLS_ECP_DP_SECP256K1_ENABLED */