diff --git a/contrib/hbcurl/core.c b/contrib/hbcurl/core.c
index 2ba39e04c0..b875187ca4 100644
--- a/contrib/hbcurl/core.c
+++ b/contrib/hbcurl/core.c
@@ -539,7 +539,7 @@ static size_t hb_curl_writefunction_callback( void * buffer, size_t size, size_t
    {
       hb_vmPushEvalSym();
       hb_vmPush( hb_curl->pWriteFunctionCallback );
-      hb_vmPushString( buffer, size * nmemb );
+      hb_vmPushString( ( const char * ) buffer, size * nmemb );
       hb_vmSend( 1 );
       hb_vmRequestRestore();
       return size * nmemb;