diff --git a/src/buffer/out/AttrRow.cpp b/src/buffer/out/AttrRow.cpp
index 548999bccc..5df4da3978 100644
--- a/src/buffer/out/AttrRow.cpp
+++ b/src/buffer/out/AttrRow.cpp
@@ -250,7 +250,7 @@ void ATTR_ROW::ReplaceAttrs(const TextAttribute& toBeReplacedAttr, const TextAtt
     if (newAttrs.size() == 1)
     {
         // Get the new color attribute we're trying to apply
-        const TextAttribute NewAttr = gsl::at(newAttrs, 0).GetAttributes();
+        const TextAttribute NewAttr = til::at(newAttrs, 0).GetAttributes();
 
         // If the existing run was only 1 element...
         // ...and the new color is the same as the old, we don't have to do anything and can exit quick.
diff --git a/src/buffer/out/OutputCellIterator.cpp b/src/buffer/out/OutputCellIterator.cpp
index 9dc5b14574..d32087fe9e 100644
--- a/src/buffer/out/OutputCellIterator.cpp
+++ b/src/buffer/out/OutputCellIterator.cpp
@@ -114,7 +114,7 @@ OutputCellIterator::OutputCellIterator(const std::wstring_view utf16Text, const
 // - legacyAttrs - One legacy color item per cell
 OutputCellIterator::OutputCellIterator(const gsl::span<const WORD> legacyAttrs) noexcept :
     _mode(Mode::LegacyAttr),
-    _currentView(s_GenerateViewLegacyAttr(gsl::at(legacyAttrs, 0))),
+    _currentView(s_GenerateViewLegacyAttr(til::at(legacyAttrs, 0))),
     _run(legacyAttrs),
     _attr(InvalidTextAttribute),
     _distance(0),
@@ -129,7 +129,7 @@ OutputCellIterator::OutputCellIterator(const gsl::span<const WORD> legacyAttrs)
 // - charInfos - Multiple cell with unicode text and legacy color data.
 OutputCellIterator::OutputCellIterator(const gsl::span<const CHAR_INFO> charInfos) noexcept :
     _mode(Mode::CharInfo),
-    _currentView(s_GenerateView(gsl::at(charInfos, 0))),
+    _currentView(s_GenerateView(til::at(charInfos, 0))),
     _run(charInfos),
     _attr(InvalidTextAttribute),
     _distance(0),
@@ -144,7 +144,7 @@ OutputCellIterator::OutputCellIterator(const gsl::span<const CHAR_INFO> charInfo
 // - cells - Multiple cells in a run
 OutputCellIterator::OutputCellIterator(const gsl::span<const OutputCell> cells) :
     _mode(Mode::Cell),
-    _currentView(s_GenerateView(gsl::at(cells, 0))),
+    _currentView(s_GenerateView(til::at(cells, 0))),
     _run(cells),
     _attr(InvalidTextAttribute),
     _distance(0),
@@ -265,7 +265,7 @@ OutputCellIterator& OutputCellIterator::operator++()
         _pos++;
         if (operator bool())
         {
-            _currentView = s_GenerateView(gsl::at(std::get<gsl::span<const OutputCell>>(_run), _pos));
+            _currentView = s_GenerateView(til::at(std::get<gsl::span<const OutputCell>>(_run), _pos));
         }
         break;
     }
@@ -275,7 +275,7 @@ OutputCellIterator& OutputCellIterator::operator++()
         _pos++;
         if (operator bool())
         {
-            _currentView = s_GenerateView(gsl::at(std::get<gsl::span<const CHAR_INFO>>(_run), _pos));
+            _currentView = s_GenerateView(til::at(std::get<gsl::span<const CHAR_INFO>>(_run), _pos));
         }
         break;
     }
@@ -285,7 +285,7 @@ OutputCellIterator& OutputCellIterator::operator++()
         _pos++;
         if (operator bool())
         {
-            _currentView = s_GenerateViewLegacyAttr(gsl::at(std::get<gsl::span<const WORD>>(_run), _pos));
+            _currentView = s_GenerateViewLegacyAttr(til::at(std::get<gsl::span<const WORD>>(_run), _pos));
         }
         break;
     }
diff --git a/src/buffer/out/TextColor.cpp b/src/buffer/out/TextColor.cpp
index e340e198ab..2040502298 100644
--- a/src/buffer/out/TextColor.cpp
+++ b/src/buffer/out/TextColor.cpp
@@ -158,9 +158,9 @@ COLORREF TextColor::GetColor(gsl::span<const COLORREF> colorTable,
             // If we find a match, return instead the bright version of this color
             for (size_t i = 0; i < 8; i++)
             {
-                if (gsl::at(colorTable, i) == defaultColor)
+                if (til::at(colorTable, i) == defaultColor)
                 {
-                    return gsl::at(colorTable, i + 8);
+                    return til::at(colorTable, i + 8);
                 }
             }
         }
@@ -173,11 +173,11 @@ COLORREF TextColor::GetColor(gsl::span<const COLORREF> colorTable,
     }
     else if (IsIndex16() && brighten)
     {
-        return gsl::at(colorTable, _index | 8);
+        return til::at(colorTable, _index | 8);
     }
     else
     {
-        return gsl::at(colorTable, _index);
+        return til::at(colorTable, _index);
     }
 }
 
diff --git a/src/host/alias.cpp b/src/host/alias.cpp
index 5c44a843ab..e58fbdb0e9 100644
--- a/src/host/alias.cpp
+++ b/src/host/alias.cpp
@@ -149,7 +149,7 @@ std::unordered_map<std::wstring,
 
     if (target.has_value() && target->size() > 0)
     {
-        gsl::at(*target, 0) = UNICODE_NULL;
+        til::at(*target, 0) = UNICODE_NULL;
     }
 
     std::wstring exeNameString(exeName);
@@ -211,7 +211,7 @@ std::unordered_map<std::wstring,
     {
         if (target.size() > 0)
         {
-            gsl::at(target, 0) = ANSI_NULL;
+            til::at(target, 0) = ANSI_NULL;
         }
 
         LockConsole();
@@ -451,7 +451,7 @@ void Alias::s_ClearCmdExeAliases()
 
     if (aliasBuffer.has_value() && aliasBuffer->size() > 0)
     {
-        gsl::at(*aliasBuffer, 0) = UNICODE_NULL;
+        til::at(*aliasBuffer, 0) = UNICODE_NULL;
     }
 
     std::wstring exeNameString(exeName);
@@ -543,7 +543,7 @@ void Alias::s_ClearCmdExeAliases()
     {
         if (alias.size() > 0)
         {
-            gsl::at(alias, 0) = '\0';
+            til::at(alias, 0) = '\0';
         }
 
         LockConsole();
@@ -698,7 +698,7 @@ void Alias::s_ClearCmdExeAliases()
     writtenOrNeeded = 0;
     if (aliasExesBuffer.has_value() && aliasExesBuffer->size() > 0)
     {
-        gsl::at(*aliasExesBuffer, 0) = UNICODE_NULL;
+        til::at(*aliasExesBuffer, 0) = UNICODE_NULL;
     }
 
     LPWSTR AliasExesBufferPtrW = aliasExesBuffer.has_value() ? aliasExesBuffer->data() : nullptr;
@@ -761,7 +761,7 @@ void Alias::s_ClearCmdExeAliases()
     {
         if (aliasExes.size() > 0)
         {
-            gsl::at(aliasExes, 0) = '\0';
+            til::at(aliasExes, 0) = '\0';
         }
 
         LockConsole();
diff --git a/src/host/dbcs.cpp b/src/host/dbcs.cpp
index fc4fd4586c..eebfcf52a7 100644
--- a/src/host/dbcs.cpp
+++ b/src/host/dbcs.cpp
@@ -67,10 +67,10 @@ DWORD UnicodeRasterFontCellMungeOnRead(const gsl::span<CHAR_INFO> buffer)
     for (DWORD iSrc = 0; iSrc < buffer.size(); iSrc++)
     {
         // If it's not a trailing byte, copy it straight over, stripping out the Leading/Trailing flags from the attributes field.
-        auto& src{ gsl::at(buffer, iSrc) };
+        auto& src{ til::at(buffer, iSrc) };
         if (!WI_IsFlagSet(src.Attributes, COMMON_LVB_TRAILING_BYTE))
         {
-            auto& dst{ gsl::at(buffer, iDst) };
+            auto& dst{ til::at(buffer, iDst) };
             dst = src;
             WI_ClearAllFlags(dst.Attributes, COMMON_LVB_SBCSDBCS);
             iDst++;
diff --git a/src/host/getset.cpp b/src/host/getset.cpp
index 77c830aedf..9c2d0e2649 100644
--- a/src/host/getset.cpp
+++ b/src/host/getset.cpp
@@ -1604,7 +1604,7 @@ void DoSrvPrivateRefreshWindow(_In_ const SCREEN_INFORMATION& screenInfo)
 
         if (title.has_value() && title->size() > 0)
         {
-            gsl::at(*title, 0) = ANSI_NULL;
+            til::at(*title, 0) = ANSI_NULL;
         }
 
         // Get the appropriate title and length depending on the mode.
@@ -1667,7 +1667,7 @@ void DoSrvPrivateRefreshWindow(_In_ const SCREEN_INFORMATION& screenInfo)
 
         if (title.size() > 0)
         {
-            gsl::at(title, 0) = ANSI_NULL;
+            til::at(title, 0) = ANSI_NULL;
         }
 
         // Figure out how big our temporary Unicode buffer must be to get the title.
@@ -1722,7 +1722,7 @@ void DoSrvPrivateRefreshWindow(_In_ const SCREEN_INFORMATION& screenInfo)
             // If we didn't copy anything back and there is space, null terminate the given buffer and return.
             if (title.size() > 0)
             {
-                gsl::at(title, 0) = ANSI_NULL;
+                til::at(title, 0) = ANSI_NULL;
                 written = 1;
             }
         }
diff --git a/src/host/history.cpp b/src/host/history.cpp
index 7475213126..e9da38a2a2 100644
--- a/src/host/history.cpp
+++ b/src/host/history.cpp
@@ -782,7 +782,7 @@ HRESULT GetConsoleCommandHistoryWImplHelper(const std::wstring_view exeName,
     writtenOrNeeded = 0;
     if (historyBuffer.size() > 0)
     {
-        gsl::at(historyBuffer, 0) = UNICODE_NULL;
+        til::at(historyBuffer, 0) = UNICODE_NULL;
     }
 
     CommandHistory* const CommandHistory = CommandHistory::s_FindByExe(exeName);
@@ -859,7 +859,7 @@ HRESULT ApiRoutines::GetConsoleCommandHistoryAImpl(const std::string_view exeNam
     {
         if (commandHistory.size() > 0)
         {
-            gsl::at(commandHistory, 0) = ANSI_NULL;
+            til::at(commandHistory, 0) = ANSI_NULL;
         }
 
         LockConsole();
diff --git a/src/inc/til/at.h b/src/inc/til/at.h
index 56001dfe87..f08f7bb08b 100644
--- a/src/inc/til/at.h
+++ b/src/inc/til/at.h
@@ -5,17 +5,52 @@
 
 namespace til
 {
+    namespace details
+    {
+        // This was lifted from gsl::details::is_span.
+        template<class T>
+        struct is_span_oracle : std::false_type
+        {
+        };
+
+#ifdef GSL_SPAN_H
+        template<class ElementType, std::size_t Extent>
+        struct is_span_oracle<gsl::span<ElementType, Extent>> : std::true_type
+        {
+        };
+#endif
+
+        template<class T>
+        struct is_span : public is_span_oracle<std::remove_cv_t<T>>
+        {
+        };
+    }
+
     // The at function declares that you've already sufficiently checked that your array access
     // is in range before retrieving an item inside it at an offset.
     // This is to save double/triple/quadruple testing in circumstances where you are already
     // pivoting on the length of a set and now want to pull elements out of it by offset
     // without checking again.
     // gsl::at will do the check again. As will .at(). And using [] will have a warning in audit.
-    template<class T>
+    // This template is explicitly disabled if T is of type gsl::span, as it would interfere with
+    // the overload below.
+    template<class T, std::enable_if_t<!details::is_span<T>::value, int> = 0>
     constexpr auto at(T& cont, const size_t i) -> decltype(cont[cont.size()])
     {
 #pragma warning(suppress : 26482) // Suppress bounds.2 check for indexing with constant expressions
 #pragma warning(suppress : 26446) // Suppress bounds.4 check for subscript operator.
         return cont[i];
     }
+
+#ifdef GSL_SPAN_H
+    // This is an overload of til::at for span that access its backing buffer directly (UNCHECKED)
+    template<typename ElementType, size_t Extent>
+    constexpr auto at(gsl::span<ElementType, Extent> span, const std::ptrdiff_t i) -> decltype(span[span.size()])
+    {
+#pragma warning(suppress : 26481) // Suppress bounds.1 check for doing pointer arithmetic
+#pragma warning(suppress : 26482) // Suppress bounds.2 check for indexing with constant expressions
+#pragma warning(suppress : 26446) // Suppress bounds.4 check for subscript operator.
+        return span.data()[i];
+    }
+#endif
 }
diff --git a/src/renderer/gdi/paint.cpp b/src/renderer/gdi/paint.cpp
index 1b68dafc93..b416510f99 100644
--- a/src/renderer/gdi/paint.cpp
+++ b/src/renderer/gdi/paint.cpp
@@ -316,7 +316,7 @@ using namespace Microsoft::Console::Render;
         // Convert data from clusters into the text array and the widths array.
         for (size_t i = 0; i < cchLine; i++)
         {
-            const auto& cluster = gsl::at(clusters, i);
+            const auto& cluster = til::at(clusters, i);
 
             // Our GDI renderer hasn't and isn't going to handle things above U+FFFF or sequences.
             // So replace anything complicated with a replacement character for drawing purposes.
diff --git a/src/terminal/parser/InputStateMachineEngine.cpp b/src/terminal/parser/InputStateMachineEngine.cpp
index 55188cdb6d..59f34e20ab 100644
--- a/src/terminal/parser/InputStateMachineEngine.cpp
+++ b/src/terminal/parser/InputStateMachineEngine.cpp
@@ -395,7 +395,7 @@ bool InputStateMachineEngine::ActionCsiDispatch(const wchar_t wch,
     // Handle intermediate characters, if any
     if (!intermediates.empty())
     {
-        switch (static_cast<CsiIntermediateCodes>(gsl::at(intermediates, 0)))
+        switch (static_cast<CsiIntermediateCodes>(til::at(intermediates, 0)))
         {
         case CsiIntermediateCodes::MOUSE_SGR:
         {
@@ -805,7 +805,7 @@ DWORD InputStateMachineEngine::_GetCursorKeysModifierState(const gsl::span<const
     DWORD modifiers = 0;
     if (_IsModified(parameters.size()) && parameters.size() >= 2)
     {
-        modifiers = _GetModifier(gsl::at(parameters, 1));
+        modifiers = _GetModifier(til::at(parameters, 1));
     }
 
     // Enhanced Keys (from https://docs.microsoft.com/en-us/windows/console/key-event-record-str):
@@ -834,7 +834,7 @@ DWORD InputStateMachineEngine::_GetGenericKeysModifierState(const gsl::span<cons
     DWORD modifiers = 0;
     if (_IsModified(parameters.size()) && parameters.size() >= 2)
     {
-        modifiers = _GetModifier(gsl::at(parameters, 1));
+        modifiers = _GetModifier(til::at(parameters, 1));
     }
 
     // Enhanced Keys (from https://docs.microsoft.com/en-us/windows/console/key-event-record-str):
@@ -1347,22 +1347,22 @@ bool InputStateMachineEngine::_GenerateWin32Key(const gsl::span<const size_t> pa
     switch (parameters.size())
     {
     case 6:
-        key.SetRepeatCount(::base::saturated_cast<WORD>(gsl::at(parameters, 5)));
+        key.SetRepeatCount(::base::saturated_cast<WORD>(til::at(parameters, 5)));
         [[fallthrough]];
     case 5:
-        key.SetActiveModifierKeys(::base::saturated_cast<DWORD>(gsl::at(parameters, 4)));
+        key.SetActiveModifierKeys(::base::saturated_cast<DWORD>(til::at(parameters, 4)));
         [[fallthrough]];
     case 4:
-        key.SetKeyDown(static_cast<bool>(gsl::at(parameters, 3)));
+        key.SetKeyDown(static_cast<bool>(til::at(parameters, 3)));
         [[fallthrough]];
     case 3:
-        key.SetCharData(static_cast<wchar_t>(gsl::at(parameters, 2)));
+        key.SetCharData(static_cast<wchar_t>(til::at(parameters, 2)));
         [[fallthrough]];
     case 2:
-        key.SetVirtualScanCode(::base::saturated_cast<WORD>(gsl::at(parameters, 1)));
+        key.SetVirtualScanCode(::base::saturated_cast<WORD>(til::at(parameters, 1)));
         [[fallthrough]];
     case 1:
-        key.SetVirtualKeyCode(::base::saturated_cast<WORD>(gsl::at(parameters, 0)));
+        key.SetVirtualKeyCode(::base::saturated_cast<WORD>(til::at(parameters, 0)));
         break;
     }
 
diff --git a/src/terminal/parser/OutputStateMachineEngine.cpp b/src/terminal/parser/OutputStateMachineEngine.cpp
index 363221cacc..4d5b4d0c8a 100644
--- a/src/terminal/parser/OutputStateMachineEngine.cpp
+++ b/src/terminal/parser/OutputStateMachineEngine.cpp
@@ -403,9 +403,9 @@ bool OutputStateMachineEngine::_IntermediateScsDispatch(const wchar_t wch,
 
     // If we have more than one intermediate, the second intermediate forms part of
     // the charset identifier. Otherwise it's identified by just the final character.
-    const auto charset = intermediates.size() > 1 ? std::make_pair(gsl::at(intermediates, 1), wch) : std::make_pair(wch, L'\0');
+    const auto charset = intermediates.size() > 1 ? std::make_pair(til::at(intermediates, 1), wch) : std::make_pair(wch, L'\0');
 
-    switch (gsl::at(intermediates, 0))
+    switch (til::at(intermediates, 0))
     {
     case L'(':
         success = _dispatch->Designate94Charset(0, charset);
@@ -1628,7 +1628,7 @@ bool OutputStateMachineEngine::s_ParseColorSpec(const std::wstring_view string,
         for (size_t component = 0; component < 3; component++)
         {
             bool foundColor = false;
-            auto& value = gsl::at(colorValues, component);
+            auto& value = til::at(colorValues, component);
             for (size_t i = 0; i < 3; i++)
             {
                 const wchar_t wch = *curr++;
diff --git a/src/terminal/parser/ut_parser/InputEngineTest.cpp b/src/terminal/parser/ut_parser/InputEngineTest.cpp
index 6873df476a..b97fa263c1 100644
--- a/src/terminal/parser/ut_parser/InputEngineTest.cpp
+++ b/src/terminal/parser/ut_parser/InputEngineTest.cpp
@@ -369,7 +369,7 @@ bool TestInteractDispatch::WindowManipulation(const DispatchTypes::WindowManipul
     for (size_t i = 0; i < parameters.size(); i++)
     {
         unsigned short actual;
-        VERIFY_SUCCEEDED(SizeTToUShort(gsl::at(parameters, i), &actual));
+        VERIFY_SUCCEEDED(SizeTToUShort(til::at(parameters, i), &actual));
         VERIFY_ARE_EQUAL(_testState->_expectedParams[i], actual);
     }
     return true;
diff --git a/src/terminal/parser/ut_parser/OutputEngineTest.cpp b/src/terminal/parser/ut_parser/OutputEngineTest.cpp
index 3fed878879..17caebefad 100644
--- a/src/terminal/parser/ut_parser/OutputEngineTest.cpp
+++ b/src/terminal/parser/ut_parser/OutputEngineTest.cpp
@@ -1557,14 +1557,14 @@ class StateMachineExternalTest final
 
             if (i < expectedOptions.size())
             {
-                expectedOption = gsl::at(expectedOptions, i);
+                expectedOption = til::at(expectedOptions, i);
             }
 
-            optionsValid = expectedOption == gsl::at(dispatch._options, i);
+            optionsValid = expectedOption == til::at(dispatch._options, i);
 
             if (!optionsValid)
             {
-                Log::Comment(NoThrowString().Format(L"Graphics option match failed, index [%zu]. Expected: '%d' Actual: '%d'", i, expectedOption, gsl::at(dispatch._options, i)));
+                Log::Comment(NoThrowString().Format(L"Graphics option match failed, index [%zu]. Expected: '%d' Actual: '%d'", i, expectedOption, til::at(dispatch._options, i)));
                 break;
             }
         }
diff --git a/src/types/utils.cpp b/src/types/utils.cpp
index 033799de69..86ff8b522a 100644
--- a/src/types/utils.cpp
+++ b/src/types/utils.cpp
@@ -425,10 +425,10 @@ void Utils::InitializeCampbellColorTableForConhost(const gsl::span<COLORREF> tab
 void Utils::SwapANSIColorOrderForConhost(const gsl::span<COLORREF> table)
 {
     THROW_HR_IF(E_INVALIDARG, table.size() < 16);
-    std::swap(gsl::at(table, 1), gsl::at(table, 4));
-    std::swap(gsl::at(table, 3), gsl::at(table, 6));
-    std::swap(gsl::at(table, 9), gsl::at(table, 12));
-    std::swap(gsl::at(table, 11), gsl::at(table, 14));
+    std::swap(til::at(table, 1), til::at(table, 4));
+    std::swap(til::at(table, 3), til::at(table, 6));
+    std::swap(til::at(table, 9), til::at(table, 12));
+    std::swap(til::at(table, 11), til::at(table, 14));
 }
 
 // Function Description: