diff --git a/src/mesa/state_tracker/st_atom_framebuffer.c b/src/mesa/state_tracker/st_atom_framebuffer.c
index 08ed3d2b454..cc5ad3d3cb7 100644
--- a/src/mesa/state_tracker/st_atom_framebuffer.c
+++ b/src/mesa/state_tracker/st_atom_framebuffer.c
@@ -200,7 +200,7 @@ st_update_framebuffer_state( struct st_context *st )
       memset(&framebuffer.zsbuf, 0, sizeof(framebuffer.zsbuf));
    }
 
-   framebuffer.viewmask = BITFIELD_MASK(num_multiview_layer);
+   framebuffer.viewmask = (uint8_t)BITFIELD_MASK(num_multiview_layer);
 
 #ifndef NDEBUG
    /* Make sure the resource binding flags were set properly */