diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index b51e9b1..27806f3 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -213,7 +213,7 @@
     /* 1. Concatenate entropy and additional data if any */
     if( additional != NULL && len != 0 )
     {
-        memcpy( seed + seedlen, additional, len );
+        mbedtls_platform_memcpy( seed + seedlen, additional, len );
         seedlen += len;
     }
 
@@ -375,7 +375,7 @@
         if( ( ret = mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V ) ) != 0 )
             goto exit;
 
-        memcpy( out, ctx->V, use_len );
+        mbedtls_platform_memcpy( out, ctx->V, use_len );
         out += use_len;
         left -= use_len;
     }
@@ -547,7 +547,7 @@
                                         unsigned char *buf, size_t len )
 {
     const unsigned char *p = data;
-    memcpy( buf, p + test_offset, len );
+    mbedtls_platform_memcpy( buf, p + test_offset, len );
     test_offset += len;
     return( 0 );
 }