diff --git a/dp32g030.cfg b/dp32g030.cfg
index 820d9f8..05e441c 100644
--- a/dp32g030.cfg
+++ b/dp32g030.cfg
@@ -91,7 +91,7 @@ proc write_image {filename address} {
 			return
 		}
 	}
-	uv_clear_sectors [expr {2*($fs+$_SECTOR_SIZE-1)/$_SECTOR_SIZE}]
+	uv_clear_sectors [expr {(($fs+$_SECTOR_SIZE-1)&(0x10000000-$_SECTOR_SIZE))/($_SECTOR_SIZE/2)}]
 	uv_flash_unlock
 	
 	set addr $address