diff --git a/patch_io.c b/patch_io.c
index 025d99b..ff28a65 100644
--- a/patch_io.c
+++ b/patch_io.c
@@ -129,7 +129,7 @@ static errcode_t patch_open(const char *name, int flags, io_channel *channel)
 
 	if (patch_io_backing_manager)
 	{
-		retval = patch_io_backing_manager->open(name, flags, &data->real);
+		retval = patch_io_backing_manager->open(name, flags & ~IO_FLAG_RW, &data->real);
 		if (retval)
 			goto cleanup;
 	}