diff --git a/src/renderer_mtl.cpp b/src/renderer_mtl.cpp
index 97fb59cfb..5112c80df 100644
--- a/src/renderer_mtl.cpp
+++ b/src/renderer_mtl.cpp
@@ -1358,11 +1358,12 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 		{
 			const TextureMtl& texture = m_textures[_handle.idx];
 
-#if BX_PLATFORM_OSX
 			MTL::BlitCommandEncoder* bce = s_renderMtl->getBlitCommandEncoder();
+#if BX_PLATFORM_OSX
 			bce->synchronizeTexture(texture.m_ptr, _layer, _mip);
-			endEncoding();
 #endif  // BX_PLATFORM_OSX
+			BX_UNUSED(bce);
+			endEncoding();
 
 			m_cmd.kick(false, true);
 			m_commandBuffer = NULL;
@@ -1496,12 +1497,12 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 				return;
 			}
 
-#if BX_PLATFORM_OSX
 			m_blitCommandEncoder = getBlitCommandEncoder();
+#if BX_PLATFORM_OSX
 			m_blitCommandEncoder->synchronizeResource(m_screenshotTarget);
+#endif  // BX_PLATFORM_OSX
 			m_blitCommandEncoder->endEncoding();
 			m_blitCommandEncoder = NULL;
-#endif  // BX_PLATFORM_OSX
 
 			m_cmd.kick(false, true);
 			m_commandBuffer = 0;
@@ -2879,6 +2880,7 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 					}
 				}
 
+				bool usedFallbackAttrib = false;
 				for (uint32_t ii = 0; Attrib::Count != program.m_used[ii]; ++ii)
 				{
 					const Attrib::Enum attr = Attrib::Enum(program.m_used[ii]);
@@ -2889,9 +2891,20 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 						vertexDesc->attributes()->object(loc)->setFormat(MTL::VertexFormatUChar2);
 						vertexDesc->attributes()->object(loc)->setBufferIndex(1);
 						vertexDesc->attributes()->object(loc)->setOffset(0);
+						usedFallbackAttrib = true;
 					}
 				}
 
+				MTL::VertexBufferLayoutDescriptor* vbld = vertexDesc->layouts()->object(1);
+
+				if (usedFallbackAttrib
+				&&  0 == vbld->stride() )
+				{
+					vbld->setStride(4);
+					vbld->setStepFunction(MTL::VertexStepFunctionConstant);
+					vbld->setStepRate(0);
+				}
+
 				if (0 < _numInstanceData)
 				{
 					uint32_t numAttribs = 0;
@@ -4960,7 +4973,7 @@ static_assert(BX_COUNTOF(s_accessNames) == Access::Count, "Invalid s_accessNames
 		if (m_blitCommandEncoder)
 		{
 			m_blitCommandEncoder->endEncoding();
-			m_blitCommandEncoder = 0;
+			m_blitCommandEncoder = NULL;
 		}
 
 		updateResolution(_render->m_resolution);