diff --git a/library/ecp.c b/library/ecp.c
index be9e42d..7b20516 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -181,6 +181,12 @@
     const mbedtls_md_type_t md_type = mbedtls_md_list()[0];
     const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_type );
 
+    if( secret_len > MBEDTLS_ECP_MAX_BYTES )
+    {
+        ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
+        goto cleanup;
+    }
+
     MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( secret,
                                                secret_bytes, secret_len ) );
 
@@ -237,6 +243,12 @@
     int ret;
     unsigned char secret_bytes[MBEDTLS_ECP_MAX_BYTES];
 
+    if( secret_len > MBEDTLS_ECP_MAX_BYTES )
+    {
+        ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
+        goto cleanup;
+    }
+
     MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( secret,
                                                secret_bytes, secret_len ) );