diff --git a/library/ecdsa.c b/library/ecdsa.c
index 1f0b37d..3ede933 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -366,7 +366,7 @@
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
     if (rs_ctx != NULL && rs_ctx->sig != NULL) {
-        mbedtls_mpi_copy(r, pr);
+        MBEDTLS_MPI_CHK(mbedtls_mpi_copy(r, pr));
     }
 #endif
 
@@ -457,7 +457,7 @@
     MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(d, data, grp_len));
     MBEDTLS_MPI_CHK(derive_mpi(grp, &h, buf, blen));
     MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&h, data + grp_len, grp_len));
-    mbedtls_hmac_drbg_seed_buf(p_rng, md_info, data, 2 * grp_len);
+    MBEDTLS_MPI_CHK(mbedtls_hmac_drbg_seed_buf(p_rng, md_info, data, 2 * grp_len));
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
     if (rs_ctx != NULL && rs_ctx->det != NULL) {