diff --git a/src/bgfx_p.h b/src/bgfx_p.h
index 1aa10fe6e..fdbcee6c9 100644
--- a/src/bgfx_p.h
+++ b/src/bgfx_p.h
@@ -3204,6 +3204,11 @@ namespace bgfx
 
 		BGFX_API_FUNC(uint32_t readTexture(TextureHandle _handle, void* _data, uint8_t _mip) )
 		{
+			BGFX_CHECK_HANDLE("readTexture", m_textureHandle, _handle);
+
+			const TextureRef& ref = m_textureRef[_handle.idx];
+			BX_CHECK(_mip < ref.m_numMips, "Invalid mip: %d num mips:", _mip, ref.m_numMips); BX_UNUSED(ref);
+
 			CommandBuffer& cmdbuf = getCommandBuffer(CommandBuffer::ReadTexture);
 			cmdbuf.write(_handle);
 			cmdbuf.write(_data);
@@ -3215,8 +3220,10 @@ namespace bgfx
 		{
 			const FrameBufferRef& ref = m_frameBufferRef[_handle.idx];
 			BX_CHECK(!ref.m_window, "Can't sample window frame buffer.");
+
 			TextureHandle textureHandle = ref.un.m_th[_attachment];
-			BX_CHECK(isValid(textureHandle), "Frame buffer texture %d is invalid.", _attachment);
+			BGFX_CHECK_HANDLE("readTexture", m_textureHandle, textureHandle);
+
 			return readTexture(textureHandle, _data,0);
 		}
 
diff --git a/src/renderer_d3d11.cpp b/src/renderer_d3d11.cpp
index 98e7a9caa..df860e310 100644
--- a/src/renderer_d3d11.cpp
+++ b/src/renderer_d3d11.cpp
@@ -1844,11 +1844,10 @@ BX_PRAGMA_DIAGNOSTIC_POP();
 		{
 			const TextureD3D11& texture = m_textures[_handle.idx];
 			D3D11_MAPPED_SUBRESOURCE mapped;
-			BX_CHECK(_mip<texture.m_numMips,"Invalid mip: %d num mips:",_mip,texture.m_numMips);
 			DX_CHECK(m_deviceCtx->Map(texture.m_ptr, _mip, D3D11_MAP_READ, 0, &mapped) );
 
-			uint32_t srcWidth  = texture.m_width>>_mip;
-			uint32_t srcHeight = texture.m_height>>_mip;
+			uint32_t srcWidth  = bx::uint32_max(1, texture.m_width >>_mip);
+			uint32_t srcHeight = bx::uint32_max(1, texture.m_height>>_mip);
 			uint8_t* src       = (uint8_t*)mapped.pData;
 			uint32_t srcPitch  = mapped.RowPitch;
 
diff --git a/src/renderer_d3d12.cpp b/src/renderer_d3d12.cpp
index 01d86879f..d7a449ea8 100644
--- a/src/renderer_d3d12.cpp
+++ b/src/renderer_d3d12.cpp
@@ -1403,7 +1403,6 @@ namespace bgfx { namespace d3d12
 
 		void readTexture(TextureHandle _handle, void* _data, uint8_t _mip ) BX_OVERRIDE
 		{
-			_mip;
 			const TextureD3D12& texture = m_textures[_handle.idx];
 
 			D3D12_RESOURCE_DESC desc = texture.m_ptr->GetDesc();
@@ -1413,7 +1412,7 @@ namespace bgfx { namespace d3d12
 			uint64_t total;
 			uint64_t srcPitch;
 			m_device->GetCopyableFootprints(&desc
-				, 0
+				, _mip
 				, 1
 				, 0
 				, &layout
@@ -1439,16 +1438,18 @@ namespace bgfx { namespace d3d12
 			finish();
 			m_commandList = m_cmd.alloc();
 
+			uint32_t srcWidth  = bx::uint32_max(1, texture.m_width >>_mip);
+			uint32_t srcHeight = bx::uint32_max(1, texture.m_height>>_mip);
 			uint8_t* src;
 			readback->Map(0, NULL, (void**)&src);
 
 			const uint8_t bpp = getBitsPerPixel(TextureFormat::Enum(texture.m_textureFormat) );
 			uint8_t* dst      = (uint8_t*)_data;
-			uint32_t dstPitch = texture.m_width*bpp/8;
+			uint32_t dstPitch = srcWidth*bpp/8;
 
 			uint32_t pitch = bx::uint32_min(uint32_t(srcPitch), dstPitch);
 
-			for (uint32_t yy = 0, height = texture.m_height; yy < height; ++yy)
+			for (uint32_t yy = 0, height = srcHeight; yy < height; ++yy)
 			{
 				memcpy(dst, src, pitch);
 
diff --git a/src/renderer_d3d9.cpp b/src/renderer_d3d9.cpp
index abe7847f6..72ac1e539 100644
--- a/src/renderer_d3d9.cpp
+++ b/src/renderer_d3d9.cpp
@@ -990,7 +990,6 @@ namespace bgfx { namespace d3d9
 		void readTexture(TextureHandle _handle, void* _data, uint8_t _mip) BX_OVERRIDE
 		{
 			TextureD3D9& texture = m_textures[_handle.idx];
-			BX_CHECK( _mip<texture.m_numMips, "Invalid mip: %d num mips:", _mip, texture.m_numMips );
 
 			D3DLOCKED_RECT lockedRect;
 			DX_CHECK(texture.m_texture2d->LockRect(_mip
@@ -999,8 +998,8 @@ namespace bgfx { namespace d3d9
 				, D3DLOCK_NO_DIRTY_UPDATE|D3DLOCK_NOSYSLOCK|D3DLOCK_READONLY
 				) );
 
-			uint32_t srcWidth  = texture.m_width>>_mip;
-			uint32_t srcHeight = texture.m_height>>_mip;
+			uint32_t srcWidth  = bx::uint32_max(1, texture.m_width >>_mip);
+			uint32_t srcHeight = bx::uint32_max(1, texture.m_height>>_mip);
 			uint32_t srcPitch  = lockedRect.Pitch;
 			uint8_t* src       = (uint8_t*)lockedRect.pBits;
 
diff --git a/src/renderer_mtl.mm b/src/renderer_mtl.mm
index 7f67ac635..b45b8a2fe 100644
--- a/src/renderer_mtl.mm
+++ b/src/renderer_mtl.mm
@@ -806,13 +806,13 @@ namespace bgfx { namespace mtl
 
 			BX_CHECK(_mip<texture.m_numMips,"Invalid mip: %d num mips:",_mip,texture.m_numMips);
 
-			uint32_t width  = texture.m_ptr.width() >> _mip;
-			uint32_t height = texture.m_ptr.height() >> _mip;
+			uint32_t srcWidth  = bx::uint32_max(1, texture.m_ptr.width()  >> _mip);
+			uint32_t srcHeight = bx::uint32_max(1, texture.m_ptr.height() >> _mip);
 			const uint8_t bpp = getBitsPerPixel(TextureFormat::Enum(texture.m_textureFormat) );
 
-			MTLRegion region = { { 0, 0, 0 }, { width, height, 1 } };
+			MTLRegion region = { { 0, 0, 0 }, { srcWidth, srcHeight, 1 } };
 
-			texture.m_ptr.getBytes(_data, width*bpp/8, 0, region, _mip, 0);
+			texture.m_ptr.getBytes(_data, srcWidth*bpp/8, 0, region, _mip, 0);
 
 			m_commandBuffer = m_commandQueue.commandBuffer();
 			retain(m_commandBuffer); //NOTE: keep alive to be useable at 'flip'