diff --git a/harbour/source/rtl/transfrm.c b/harbour/source/rtl/transfrm.c
index 6edc0f857e..99c5f7d4ee 100644
--- a/harbour/source/rtl/transfrm.c
+++ b/harbour/source/rtl/transfrm.c
@@ -368,7 +368,7 @@ HB_FUNC( TRANSFORM )
          if( uiPicFlags & PF_STRING )
          {
             char * szPic2 = hb_itemGetCPtr( pPic );
-            int ulLen = atol( szPic2 + 2 );
+            ULONG ulLen = ( ULONG ) atol( szPic2 + 2 );
 
             if( ulLen & ( ulLen <= ulExpLen ) )
             {