diff --git a/src/renderer_mtl.mm b/src/renderer_mtl.mm
index f6143cb56..453b6fb59 100644
--- a/src/renderer_mtl.mm
+++ b/src/renderer_mtl.mm
@@ -3045,6 +3045,7 @@ namespace bgfx { namespace mtl
 	{
 		BX_UNUSED(_format, _depthFormat);
 		m_swapChain = BX_NEW(g_allocator, SwapChainMtl);
+		m_num = 0;
 		m_width     = _width;
 		m_height    = _height;
 		m_nwh       = _nwh;