diff --git a/library/x509_csr.c b/library/x509_csr.c
index f5dc034..0bec03c 100644
--- a/library/x509_csr.c
+++ b/library/x509_csr.c
@@ -114,7 +114,7 @@
     if( p == NULL )
         return( MBEDTLS_ERR_X509_ALLOC_FAILED );
 
-    memcpy( p, buf, buflen );
+    mbedtls_platform_memcpy( p, buf, buflen );
 
     csr->raw.p = p;
     csr->raw.len = len;