diff --git a/src/host/ut_host/VtIoTests.cpp b/src/host/ut_host/VtIoTests.cpp
index 6ef1113b86b..599a29caec4 100644
--- a/src/host/ut_host/VtIoTests.cpp
+++ b/src/host/ut_host/VtIoTests.cpp
@@ -254,6 +254,145 @@ void VtIoTests::DtorTestStackAllocMany()
     }
 }
 
+class MockRenderData : public IRenderData, IUiaData
+{
+public:
+    Microsoft::Console::Types::Viewport GetViewport() noexcept override
+    {
+        return Microsoft::Console::Types::Viewport{};
+    }
+
+    COORD GetTextBufferEndPosition() const noexcept override
+    {
+        return COORD{};
+    }
+
+    const TextBuffer& GetTextBuffer() noexcept override
+    {
+        FAIL_FAST_HR(E_NOTIMPL);
+    }
+
+    const FontInfo& GetFontInfo() noexcept override
+    {
+        FAIL_FAST_HR(E_NOTIMPL);
+    }
+
+    std::vector<Microsoft::Console::Types::Viewport> GetSelectionRects() noexcept override
+    {
+        return std::vector<Microsoft::Console::Types::Viewport>{};
+    }
+
+    void LockConsole() noexcept override
+    {
+    }
+
+    void UnlockConsole() noexcept override
+    {
+    }
+
+    const TextAttribute GetDefaultBrushColors() noexcept override
+    {
+        return TextAttribute{};
+    }
+
+    std::pair<COLORREF, COLORREF> GetAttributeColors(const TextAttribute& /*attr*/) const noexcept override
+    {
+        return std::make_pair(COLORREF{}, COLORREF{});
+    }
+
+    COORD GetCursorPosition() const noexcept override
+    {
+        return COORD{};
+    }
+
+    bool IsCursorVisible() const noexcept override
+    {
+        return false;
+    }
+
+    bool IsCursorOn() const noexcept override
+    {
+        return false;
+    }
+
+    ULONG GetCursorHeight() const noexcept override
+    {
+        return 42ul;
+    }
+
+    CursorType GetCursorStyle() const noexcept override
+    {
+        return CursorType::FullBox;
+    }
+
+    ULONG GetCursorPixelWidth() const noexcept override
+    {
+        return 12ul;
+    }
+
+    COLORREF GetCursorColor() const noexcept override
+    {
+        return COLORREF{};
+    }
+
+    bool IsCursorDoubleWidth() const override
+    {
+        return false;
+    }
+
+    bool IsScreenReversed() const noexcept override
+    {
+        return false;
+    }
+
+    const std::vector<RenderOverlay> GetOverlays() const noexcept override
+    {
+        return std::vector<RenderOverlay>{};
+    }
+
+    const bool IsGridLineDrawingAllowed() noexcept override
+    {
+        return false;
+    }
+
+    const std::wstring GetConsoleTitle() const noexcept override
+    {
+        return std::wstring{};
+    }
+
+    const bool IsSelectionActive() const override
+    {
+        return false;
+    }
+
+    const bool IsBlockSelection() const noexcept override
+    {
+        return false;
+    }
+
+    void ClearSelection() override
+    {
+    }
+
+    void SelectNewRegion(const COORD /*coordStart*/, const COORD /*coordEnd*/) override
+    {
+    }
+
+    const COORD GetSelectionAnchor() const noexcept
+    {
+        return COORD{};
+    }
+
+    const COORD GetSelectionEnd() const noexcept
+    {
+        return COORD{};
+    }
+
+    void ColorSelection(const COORD /*coordSelectionStart*/, const COORD /*coordSelectionEnd*/, const TextAttribute /*attr*/)
+    {
+    }
+};
+
 void VtIoTests::RendererDtorAndThread()
 {
     Log::Comment(NoThrowString().Format(
@@ -261,9 +400,10 @@ void VtIoTests::RendererDtorAndThread()
 
     for (int i = 0; i < 16; ++i)
     {
+        auto data = std::make_unique<MockRenderData>();
         auto thread = std::make_unique<Microsoft::Console::Render::RenderThread>();
         auto* pThread = thread.get();
-        auto pRenderer = std::make_unique<Microsoft::Console::Render::Renderer>(nullptr, nullptr, 0, std::move(thread));
+        auto pRenderer = std::make_unique<Microsoft::Console::Render::Renderer>(data.get(), nullptr, 0, std::move(thread));
         VERIFY_SUCCEEDED(pThread->Initialize(pRenderer.get()));
         // Sleep for a hot sec to make sure the thread starts before we enable painting
         // If you don't, the thread might wait on the paint enabled event AFTER
@@ -286,9 +426,10 @@ void VtIoTests::RendererDtorAndThreadAndDx()
 
     for (int i = 0; i < 16; ++i)
     {
+        auto data = std::make_unique<MockRenderData>();
         auto thread = std::make_unique<Microsoft::Console::Render::RenderThread>();
         auto* pThread = thread.get();
-        auto pRenderer = std::make_unique<Microsoft::Console::Render::Renderer>(nullptr, nullptr, 0, std::move(thread));
+        auto pRenderer = std::make_unique<Microsoft::Console::Render::Renderer>(data.get(), nullptr, 0, std::move(thread));
         VERIFY_SUCCEEDED(pThread->Initialize(pRenderer.get()));
 
         auto dxEngine = std::make_unique<::Microsoft::Console::Render::DxEngine>();
diff --git a/src/renderer/base/renderer.cpp b/src/renderer/base/renderer.cpp
index f382dbd7c07..bdda98bc3cf 100644
--- a/src/renderer/base/renderer.cpp
+++ b/src/renderer/base/renderer.cpp
@@ -26,13 +26,12 @@ Renderer::Renderer(IRenderData* pData,
                    _In_reads_(cEngines) IRenderEngine** const rgpEngines,
                    const size_t cEngines,
                    std::unique_ptr<IRenderThread> thread) :
-    _pData(pData),
+    _pData(THROW_HR_IF_NULL(E_INVALIDARG, pData)),
     _pThread{ std::move(thread) },
     _destructing{ false },
-    _clusterBuffer{}
+    _clusterBuffer{},
+    _viewport{ pData->GetViewport() }
 {
-    _srViewportPrevious = { 0 };
-
     for (size_t i = 0; i < cEngines; i++)
     {
         IRenderEngine* engine = rgpEngines[i];
@@ -208,7 +207,7 @@ void Renderer::TriggerSystemRedraw(const RECT* const prcDirtyClient)
 // - <none>
 void Renderer::TriggerRedraw(const Viewport& region)
 {
-    Viewport view = _pData->GetViewport();
+    Viewport view = _viewport;
     SMALL_RECT srUpdateRegion = region.ToExclusive();
 
     if (view.TrimToViewport(&srUpdateRegion))
@@ -357,7 +356,7 @@ void Renderer::TriggerSelection()
 // - True if something changed and we scrolled. False otherwise.
 bool Renderer::_CheckViewportAndScroll()
 {
-    SMALL_RECT const srOldViewport = _srViewportPrevious;
+    SMALL_RECT const srOldViewport = _viewport.ToInclusive();
     SMALL_RECT const srNewViewport = _pData->GetViewport().ToInclusive();
 
     COORD coordDelta;
@@ -369,7 +368,7 @@ bool Renderer::_CheckViewportAndScroll()
         LOG_IF_FAILED(engine->UpdateViewport(srNewViewport));
     }
 
-    _srViewportPrevious = srNewViewport;
+    _viewport = Viewport::FromInclusive(srNewViewport);
 
     // If we're keeping some buffers between calls, let them know about the viewport size
     // so they can prepare the buffers for changes to either preallocate memory at once
diff --git a/src/renderer/base/renderer.hpp b/src/renderer/base/renderer.hpp
index 6c30e0f4ee6..db6dc6d3875 100644
--- a/src/renderer/base/renderer.hpp
+++ b/src/renderer/base/renderer.hpp
@@ -120,7 +120,7 @@ namespace Microsoft::Console::Render
 
         [[nodiscard]] HRESULT _PerformScrolling(_In_ IRenderEngine* const pEngine);
 
-        SMALL_RECT _srViewportPrevious;
+        Microsoft::Console::Types::Viewport _viewport;
 
         static constexpr float _shrinkThreshold = 0.8f;
         std::vector<Cluster> _clusterBuffer;