diff --git a/.github/actions/spell-check/expect/expect.txt b/.github/actions/spell-check/expect/expect.txt
index 61a6c95d77..2ff98f8e89 100644
--- a/.github/actions/spell-check/expect/expect.txt
+++ b/.github/actions/spell-check/expect/expect.txt
@@ -202,6 +202,7 @@ capslock
 CARETBLINKINGENABLED
 CARRIAGERETURN
 cascadia
+cassert
 catid
 cazamor
 CBash
@@ -268,12 +269,14 @@ clipbrd
 CLIPCHILDREN
 CLIPSIBLINGS
 cliutils
+clocale
 closetest
 cloudconsole
 cls
 CLSCTX
 clsid
 CLUSTERMAP
+cmath
 cmatrix
 cmder
 CMDEXT
@@ -416,12 +419,16 @@ Csr
 csrmsg
 CSRSS
 csrutil
+cstdarg
+cstddef
 cstdio
+cstdlib
 cstr
 cstring
 cstyle
 CSwitch
 CText
+ctime
 ctl
 ctlseqs
 Ctlv
diff --git a/samples/ConPTY/EchoCon/EchoCon/stdafx.h b/samples/ConPTY/EchoCon/EchoCon/stdafx.h
index 1fa6ee20bf..444956b91c 100644
--- a/samples/ConPTY/EchoCon/EchoCon/stdafx.h
+++ b/samples/ConPTY/EchoCon/EchoCon/stdafx.h
@@ -7,7 +7,7 @@
 
 #include "targetver.h"
 
-#include <stdio.h>
+#include <cstdio>
 #include <tchar.h>
 
 // TODO: reference additional headers your program requires here
diff --git a/src/cascadia/TerminalConnection/AzureConnection.cpp b/src/cascadia/TerminalConnection/AzureConnection.cpp
index ddffdc9c6e..ae7b3a5601 100644
--- a/src/cascadia/TerminalConnection/AzureConnection.cpp
+++ b/src/cascadia/TerminalConnection/AzureConnection.cpp
@@ -10,7 +10,7 @@
 #include "AzureConnection.h"
 #include "AzureClientID.h"
 #include <sstream>
-#include <stdlib.h>
+#include <cstdlib>
 #include <LibraryResources.h>
 #include <unicode.hpp>
 
diff --git a/src/cascadia/WindowsTerminal/pch.h b/src/cascadia/WindowsTerminal/pch.h
index 1062d1bf7c..7d82654a5e 100644
--- a/src/cascadia/WindowsTerminal/pch.h
+++ b/src/cascadia/WindowsTerminal/pch.h
@@ -25,8 +25,8 @@ Abstract:
 
 #include <windows.h>
 #include <UIAutomation.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cstdlib>
+#include <cstring>
 #include <shellscalingapi.h>
 #include <windowsx.h>
 
diff --git a/src/host/conattrs.cpp b/src/host/conattrs.cpp
index b64ff757fe..5705f3a36d 100644
--- a/src/host/conattrs.cpp
+++ b/src/host/conattrs.cpp
@@ -15,7 +15,7 @@ Author(s):
 
 #include "precomp.h"
 #include "..\inc\conattrs.hpp"
-#include <math.h>
+#include <cmath>
 
 struct _HSL
 {
diff --git a/src/host/precomp.h b/src/host/precomp.h
index ed00242ba1..4368ec07db 100644
--- a/src/host/precomp.h
+++ b/src/host/precomp.h
@@ -56,7 +56,7 @@ Abstract:
 #include <intsafe.h>
 #pragma prefast(pop)
 #include <strsafe.h>
-#include <wchar.h>
+#include <cwchar>
 #include <mmsystem.h>
 #include "utils.hpp"
 
diff --git a/src/host/screenInfo.cpp b/src/host/screenInfo.cpp
index 96dff5edcb..ea54bd8ad3 100644
--- a/src/host/screenInfo.cpp
+++ b/src/host/screenInfo.cpp
@@ -11,7 +11,7 @@
 #include "handle.h"
 #include "../buffer/out/CharRow.hpp"
 
-#include <math.h>
+#include <cmath>
 #include "../interactivity/inc/ServiceLocator.hpp"
 #include "../types/inc/Viewport.hpp"
 #include "../types/inc/GlyphWidth.hpp"
diff --git a/src/host/telemetry.cpp b/src/host/telemetry.cpp
index 4f4d1bb10b..2e4b90aaac 100644
--- a/src/host/telemetry.cpp
+++ b/src/host/telemetry.cpp
@@ -6,7 +6,7 @@
 #include <Intsafe.h>
 #include "Shlwapi.h"
 #include "telemetry.hpp"
-#include <time.h>
+#include <ctime>
 
 #include "history.h"
 
diff --git a/src/host/ut_host/UtilsTests.cpp b/src/host/ut_host/UtilsTests.cpp
index c913396bae..9a266a0742 100644
--- a/src/host/ut_host/UtilsTests.cpp
+++ b/src/host/ut_host/UtilsTests.cpp
@@ -9,7 +9,7 @@
 
 #include "globals.h"
 
-#include <time.h>
+#include <ctime>
 
 #include "utils.hpp"
 
diff --git a/src/inc/LibraryIncludes.h b/src/inc/LibraryIncludes.h
index f266d37e47..169059f086 100644
--- a/src/inc/LibraryIncludes.h
+++ b/src/inc/LibraryIncludes.h
@@ -38,7 +38,7 @@
 #include <vector>
 #include <unordered_map>
 #include <iterator>
-#include <math.h>
+#include <cmath>
 #include <sstream>
 #include <fstream>
 #include <iomanip>
diff --git a/src/propsheet/precomp.h b/src/propsheet/precomp.h
index 27a1f0eb94..adbeb22668 100644
--- a/src/propsheet/precomp.h
+++ b/src/propsheet/precomp.h
@@ -27,9 +27,9 @@
 #include "LibraryIncludes.h"
 
 #include <windowsx.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <stddef.h>
+#include <cstdlib>
+#include <cstdio>
+#include <cstddef>
 #include <winbase.h>
 #include <winconp.h>
 #include <wingdi.h>
@@ -43,7 +43,7 @@
 
 #include <strsafe.h>
 #include <intsafe.h>
-#include <wchar.h>
+#include <cwchar>
 #include <shellapi.h>
 
 #include "strid.h"
diff --git a/src/renderer/dx/precomp.h b/src/renderer/dx/precomp.h
index d77791ddc3..1d17a00bb4 100644
--- a/src/renderer/dx/precomp.h
+++ b/src/renderer/dx/precomp.h
@@ -13,7 +13,7 @@
 #include "..\host\conddkrefs.h"
 #include <condrv.h>
 
-#include <math.h>
+#include <cmath>
 
 #include <algorithm>
 #include <exception>
diff --git a/src/renderer/gdi/precomp.h b/src/renderer/gdi/precomp.h
index 4e463adb2a..9043621d11 100644
--- a/src/renderer/gdi/precomp.h
+++ b/src/renderer/gdi/precomp.h
@@ -10,7 +10,7 @@ Abstract:
 - Avoid including internal project headers. Instead include them only in the classes that need them (helps with test project building).
 --*/
 
-#include <wchar.h>
+#include <cwchar>
 #include <sal.h>
 
 // This includes support libraries from the CRT, STL, WIL, and GSL
diff --git a/src/renderer/gdi/tool/main.cpp b/src/renderer/gdi/tool/main.cpp
index 1317fbbe4b..c26b129f64 100644
--- a/src/renderer/gdi/tool/main.cpp
+++ b/src/renderer/gdi/tool/main.cpp
@@ -1,6 +1,6 @@
 #include "precomp.h"
-#include <stdio.h>
-#include <wchar.h>
+#include <cstdio>
+#include <cwchar>
 #include "wincon.h"
 
 int CALLBACK EnumFontFamiliesExProc(ENUMLOGFONTEX* lpelfe, NEWTEXTMETRICEX* lpntme, int FontType, LPARAM lParam)
diff --git a/src/renderer/vt/precomp.h b/src/renderer/vt/precomp.h
index 4e463adb2a..9043621d11 100644
--- a/src/renderer/vt/precomp.h
+++ b/src/renderer/vt/precomp.h
@@ -10,7 +10,7 @@ Abstract:
 - Avoid including internal project headers. Instead include them only in the classes that need them (helps with test project building).
 --*/
 
-#include <wchar.h>
+#include <cwchar>
 #include <sal.h>
 
 // This includes support libraries from the CRT, STL, WIL, and GSL
diff --git a/src/renderer/vt/state.cpp b/src/renderer/vt/state.cpp
index c03b657463..a950bf99d7 100644
--- a/src/renderer/vt/state.cpp
+++ b/src/renderer/vt/state.cpp
@@ -8,7 +8,7 @@
 
 // For _vcprintf
 #include <conio.h>
-#include <stdarg.h>
+#include <cstdarg>
 
 #pragma hdrstop
 
diff --git a/src/renderer/wddmcon/precomp.h b/src/renderer/wddmcon/precomp.h
index 94e46775b1..634e8a0113 100644
--- a/src/renderer/wddmcon/precomp.h
+++ b/src/renderer/wddmcon/precomp.h
@@ -13,7 +13,7 @@
 
 #include <condrv.h>
 
-#include <math.h>
+#include <cmath>
 
 #include <exception>
 #include <typeinfo>
diff --git a/src/terminal/adapter/precomp.h b/src/terminal/adapter/precomp.h
index 660c85780e..3bac1b4b2a 100644
--- a/src/terminal/adapter/precomp.h
+++ b/src/terminal/adapter/precomp.h
@@ -13,7 +13,7 @@ Abstract:
 // This includes support libraries from the CRT, STL, WIL, and GSL
 #include "LibraryIncludes.h"
 
-#include <math.h>
+#include <cmath>
 #define ENABLE_INTSAFE_SIGNED_FUNCTIONS
 #include <intsafe.h>
 
diff --git a/src/terminal/parser/ft_fuzzer/fuzzing_directed.h b/src/terminal/parser/ft_fuzzer/fuzzing_directed.h
index 0cdfb835b9..1095d7f061 100644
--- a/src/terminal/parser/ft_fuzzer/fuzzing_directed.h
+++ b/src/terminal/parser/ft_fuzzer/fuzzing_directed.h
@@ -21,7 +21,7 @@
 
 #include <vector>
 #include <limits>
-#include <assert.h>
+#include <cassert>
 #include <strsafe.h>
 
 #pragma warning(disable : 4505)
diff --git a/src/terminal/parser/ft_fuzzer/stdafx.h b/src/terminal/parser/ft_fuzzer/stdafx.h
index ca71085db2..f023cdd904 100644
--- a/src/terminal/parser/ft_fuzzer/stdafx.h
+++ b/src/terminal/parser/ft_fuzzer/stdafx.h
@@ -7,7 +7,7 @@
 
 #include <windows.h>
 #include <shlwapi.h>
-#include <stdio.h>
+#include <cstdio>
 
 // This includes support libraries from the CRT, STL, WIL, and GSL
 #include "LibraryIncludes.h"
diff --git a/src/terminal/parser/ft_fuzzwrapper/precomp.h b/src/terminal/parser/ft_fuzzwrapper/precomp.h
index 6aa9619718..f87cf15a18 100644
--- a/src/terminal/parser/ft_fuzzwrapper/precomp.h
+++ b/src/terminal/parser/ft_fuzzwrapper/precomp.h
@@ -18,8 +18,8 @@ Abstract:
 
 #include <windows.h>
 
-#include <stdlib.h>
-#include <stdio.h>
+#include <cstdlib>
+#include <cstdio>
 
 // This includes support libraries from the CRT, STL, WIL, and GSL
 #include "LibraryIncludes.h"
diff --git a/src/terminal/parser/telemetry.hpp b/src/terminal/parser/telemetry.hpp
index 6f1b06ebb6..ed7ba93dd5 100644
--- a/src/terminal/parser/telemetry.hpp
+++ b/src/terminal/parser/telemetry.hpp
@@ -14,7 +14,7 @@ Abstract:
 #include <windows.h>
 #include <winmeta.h>
 #include <TraceLoggingProvider.h>
-#include "limits.h"
+#include "climits"
 
 TRACELOGGING_DECLARE_PROVIDER(g_hConsoleVirtTermParserEventTraceProvider);
 
diff --git a/src/tools/buffersize/main.cpp b/src/tools/buffersize/main.cpp
index b833e890be..9cfb7338ca 100644
--- a/src/tools/buffersize/main.cpp
+++ b/src/tools/buffersize/main.cpp
@@ -7,15 +7,15 @@
 #include <wil\resource.h>
 #include <wil\wistd_functional.h>
 #include <wil\wistd_memory.h>
-#include <stdlib.h> /* srand, rand */
-#include <time.h> /* time */
+#include <cstdlib> /* srand, rand */
+#include <ctime> /* time */
 
 #include <deque>
 #include <memory>
 #include <vector>
 #include <string>
 #include <sstream>
-#include <assert.h>
+#include <cassert>
 
 using namespace std;
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/tools/closetest/closetest.cpp b/src/tools/closetest/closetest.cpp
index 59db98e73a..16d2a184fa 100644
--- a/src/tools/closetest/closetest.cpp
+++ b/src/tools/closetest/closetest.cpp
@@ -193,12 +193,12 @@ EXAMPLE 3: race condition between process cleanup and close signaling
 #endif
 
 #include <windows.h>
-#include <assert.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <wchar.h>
-#include <locale.h>
+#include <cassert>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <cwchar>
+#include <clocale>
 
 #include <algorithm>
 #include <array>
diff --git a/src/tools/echokey/main.cpp b/src/tools/echokey/main.cpp
index 4958cceac7..e391754e34 100644
--- a/src/tools/echokey/main.cpp
+++ b/src/tools/echokey/main.cpp
@@ -6,10 +6,10 @@
 // System headers
 #include <windows.h>
 
-// Standard library C-style
-#include <wchar.h>
-#include <stdlib.h>
-#include <stdio.h>
+// Standard C++ library
+#include <cwchar>
+#include <cstdlib>
+#include <cstdio>
 
 #include <string>
 using namespace std;
diff --git a/src/tools/integrity/exeuwp/consoleuwp.cpp b/src/tools/integrity/exeuwp/consoleuwp.cpp
index 694e71404c..650e168f43 100644
--- a/src/tools/integrity/exeuwp/consoleuwp.cpp
+++ b/src/tools/integrity/exeuwp/consoleuwp.cpp
@@ -2,8 +2,8 @@
 // Licensed under the MIT license.
 
 #include <windows.h>
-#include <Stdlib.h>
-#include <stdio.h>
+#include <cstdlib>
+#include <cstdio>
 #include <appmodel.h>
 #include <strsafe.h>
 
diff --git a/src/tools/lnkd/precomp.h b/src/tools/lnkd/precomp.h
index 62cf387033..1c7723983e 100644
--- a/src/tools/lnkd/precomp.h
+++ b/src/tools/lnkd/precomp.h
@@ -6,8 +6,8 @@
 #include <ntrtl.h>
 #include <nturtl.h>
 #include <windows.h>
-#include <wchar.h>
-#include <stdio.h>
+#include <cwchar>
+#include <cstdio>
 #include <shlwapi.h>
 #include <propvarutil.h>
 #include <initguid.h>
diff --git a/src/tools/pixels/precomp.h b/src/tools/pixels/precomp.h
index f8fba2b287..15020049fb 100644
--- a/src/tools/pixels/precomp.h
+++ b/src/tools/pixels/precomp.h
@@ -9,7 +9,7 @@
 #include <nturtl.h>
 #include <windows.h>
 
-#include <stdio.h>
+#include <cstdio>
 #include <shlwapi.h>
 #include <propvarutil.h>
 #include <initguid.h>
@@ -22,9 +22,9 @@
 #include <sal.h>
 
 // Standard library C-style
-#include <wchar.h>
-#include <stdlib.h>
-#include <stdio.h>
+#include <cwchar>
+#include <cstdlib>
+#include <cstdio>
 
 // This includes support libraries from the CRT, STL, WIL, and GSL
 #include "LibraryIncludes.h"
diff --git a/src/tools/test/precomp.h b/src/tools/test/precomp.h
index 2a2f83f423..37d8a65130 100644
--- a/src/tools/test/precomp.h
+++ b/src/tools/test/precomp.h
@@ -6,8 +6,8 @@
 #include <ntrtl.h>
 #include <nturtl.h>
 #include <windows.h>
-#include <wchar.h>
-#include <stdio.h>
+#include <cwchar>
+#include <cstdio>
 #include <shlwapi.h>
 #include <propvarutil.h>
 #include <initguid.h>
diff --git a/src/tools/vtpipeterm/VtConsole.cpp b/src/tools/vtpipeterm/VtConsole.cpp
index 99ede8c821..bd244daaa9 100644
--- a/src/tools/vtpipeterm/VtConsole.cpp
+++ b/src/tools/vtpipeterm/VtConsole.cpp
@@ -4,15 +4,15 @@
 #include "..\..\inc\conpty.h"
 #include "VtConsole.hpp"
 
-#include <stdlib.h> /* srand, rand */
-#include <time.h> /* time */
+#include <cstdlib> /* srand, rand */
+#include <ctime> /* time */
 
 #include <deque>
 #include <vector>
 #include <string>
 #include <sstream>
 #include <iomanip>
-#include <assert.h>
+#include <cassert>
 #include <wincon.h>
 
 VtConsole::VtConsole(PipeReadCallback const pfnReadCallback,
diff --git a/src/tools/vtpipeterm/main.cpp b/src/tools/vtpipeterm/main.cpp
index 3bc1abed75..c5e165618c 100644
--- a/src/tools/vtpipeterm/main.cpp
+++ b/src/tools/vtpipeterm/main.cpp
@@ -7,15 +7,15 @@
 #include <wil\resource.h>
 #include <wil\wistd_functional.h>
 #include <wil\wistd_memory.h>
-#include <stdlib.h> /* srand, rand */
-#include <time.h> /* time */
+#include <cstdlib> /* srand, rand */
+#include <ctime> /* time */
 
 #include <deque>
 #include <memory>
 #include <vector>
 #include <string>
 #include <sstream>
-#include <assert.h>
+#include <cassert>
 
 #include "VtConsole.hpp"
 
diff --git a/src/tsf/precomp.h b/src/tsf/precomp.h
index 374081390f..eb95d0f1f2 100644
--- a/src/tsf/precomp.h
+++ b/src/tsf/precomp.h
@@ -22,22 +22,22 @@ Notes:
 #define NOMINMAX
 
 #define _OLEAUT32_
-#include <windows.h>
 #include <ole2.h>
+#include <windows.h>
 
 extern "C" {
 #include <winuser.h>
 
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-#include <limits.h>
-
 #include <ime.h>
-#include <strsafe.h>
 #include <intsafe.h>
+#include <strsafe.h>
 }
 
+#include <climits>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
 #include <msctf.h> // Cicero header
 #include <tsattrs.h> // ITextStore standard attributes
 
@@ -48,5 +48,5 @@ extern "C" {
 
 #include "globals.h"
 
-#include "TfCtxtComp.h"
 #include "ConsoleTSF.h"
+#include "TfCtxtComp.h"