diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 10a7be6..9c16c5e 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -11,13 +11,21 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest]
+        include:
+          - { os: ubuntu-latest,  name: Linux }
+          - { os: macos-latest,   name: macOS }
+          - { os: windows-latest, name: Windows (MSVC) }
     runs-on: ${{ matrix.os }}
+    name: ${{ matrix.name }}
     steps:
       - uses: actions/checkout@v4
       - name: Configure
         run: cmake -B build -DCMAKE_BUILD_TYPE=Release
       - name: Build
-        run: cmake --build build
-      - name: Smoke test
+        run: cmake --build build --config Release
+      - name: Smoke test (Unix)
+        if: runner.os != 'Windows'
         run: ./build/cli/uc2 -h
+      - name: Smoke test (Windows)
+        if: runner.os == 'Windows'
+        run: .\build\cli\Release\uc2.exe -h
diff --git a/.gitignore b/.gitignore
index e40e07b..e3f5fc3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 # Build
 build/
+build-*/
 cmake-build-*/
 
 # IDE
diff --git a/cli/CMakeLists.txt b/cli/CMakeLists.txt
index 1d4be59..3125213 100644
--- a/cli/CMakeLists.txt
+++ b/cli/CMakeLists.txt
@@ -15,12 +15,22 @@ target_compile_features(uc2-cli PRIVATE c_std_99)
 
 if(WIN32)
     target_sources(uc2-cli PRIVATE src/compat/compat_win32.c)
+    # Shared compat headers (err.h, fnmatch.h) — both MSVC and MinGW lack these
     target_include_directories(uc2-cli PRIVATE src/compat/include)
+    if(MSVC)
+        # MSVC standalone headers (unistd.h, utime.h, getopt.h) — no #include_next
+        target_sources(uc2-cli PRIVATE src/compat/getopt.c)
+        target_include_directories(uc2-cli PRIVATE src/compat/include/msvc)
+    else()
+        # MinGW/Clang: headers that wrap system headers via #include_next
+        target_include_directories(uc2-cli PRIVATE src/compat/include/posix)
+    endif()
     target_compile_definitions(uc2-cli PRIVATE
+        NO_OLDNAMES
         g_err g_errx g_warn g_warnx g_vwarn g_vwarnx g_verr g_verrx
         g_getprogname g_setlinebuf g_fnmatch
         g_compat__utf8_console g_compat__wpath g_fopen
-        g_access g_mkdir g_utime
+        g_access g_unlink g_chdir g_mkdir g_chmod g_utime
     )
 elseif(DJGPP)
     target_sources(uc2-cli PRIVATE src/compat/compat_dos.c)
diff --git a/cli/src/compat/compat_win32.c b/cli/src/compat/compat_win32.c
index d535b11..d5b923c 100644
--- a/cli/src/compat/compat_win32.c
+++ b/cli/src/compat/compat_win32.c
@@ -1,4 +1,7 @@
-/* Copyright © Jan Bobrowski 2020 / Licence: LGPL */
+/* Win32 compatibility layer for UC2 CLI.
+   Provides POSIX/BSD functions missing from MSVC and MinGW.
+   All file operations use wide-char Windows APIs for UTF-8 support.
+   Copyright (c) Jan Bobrowski 2020 / Licence: LGPL */
 
 #define NO_OLDNAMES
 #include <stdlib.h>
@@ -110,7 +113,7 @@ const char *getprogname(void)
 {
 	static char name[256];
 	if (!name[0]) {
-#ifdef _pgmptr
+#ifdef _WIN32
 		char *p = _pgmptr;
 		char *q = p;
 		int n;
@@ -215,6 +218,18 @@ wchar_t *compat__wpath(const char *path);
 
 #ifdef g_compat__utf8_console
 #include <fcntl.h>
+#ifdef _MSC_VER
+/* MSVC: use CRT initializer table (.CRT$XCU) instead of GCC constructor */
+static void __cdecl compat__utf8_console_init(void)
+{
+	setvbuf(stdout, 0, _IOFBF, 1<<16);
+	setvbuf(stderr, 0, _IOFBF, 1<<16);
+	SetConsoleOutputCP(CP_UTF8);
+}
+#pragma section(".CRT$XCU", read)
+__declspec(allocate(".CRT$XCU"))
+static void (__cdecl *compat__utf8_console_p)(void) = compat__utf8_console_init;
+#else
 __attribute__((constructor))
 void compat__utf8_console(void)
 {
@@ -223,6 +238,7 @@ void compat__utf8_console(void)
 	SetConsoleOutputCP(CP_UTF8);
 }
 #endif
+#endif
 
 #ifdef g_compat__wpath
 wchar_t *compat__wpath(const char *path)
@@ -253,6 +269,22 @@ int access(const char *path, int mode)
 }
 #endif
 
+#ifdef g_unlink
+int unlink(const char *path)
+{
+	wchar_t *wpath = compat__wpath(path);
+	return wpath ? _wunlink(wpath) : -1;
+}
+#endif
+
+#ifdef g_chdir
+int chdir(const char *path)
+{
+	wchar_t *wpath = compat__wpath(path);
+	return wpath ? _wchdir(wpath) : -1;
+}
+#endif
+
 #ifdef g_mkdir
 int mkdir(const char *path, int mode)
 {
@@ -266,14 +298,27 @@ int mkdir(const char *path, int mode)
 }
 #endif
 
+#ifdef g_chmod
+int chmod(const char *path, int mode)
+{
+	wchar_t *wpath = compat__wpath(path);
+	return wpath ? _wchmod(wpath, mode) : -1;
+}
+#endif
+
 #ifdef g_utime
 #include <sys/utime.h>
+#ifdef _MSC_VER
+/* MSVC's <sys/utime.h> hides utimbuf behind NO_OLDNAMES */
+#include <time.h>
+struct utimbuf { time_t actime; time_t modtime; };
+#endif
 int utime(const char *path, struct utimbuf *ut)
 {
 	wchar_t *wpath = compat__wpath(path);
 	if (!wpath)
 		return -1;
-	struct __utimbuf32 wut = {.actime = ut->actime, .modtime = ut->modtime};
+	struct __utimbuf32 wut = {.actime = (long)ut->actime, .modtime = (long)ut->modtime};
 	return _wutime32(wpath, &wut);
 }
 #endif
diff --git a/cli/src/compat/getopt.c b/cli/src/compat/getopt.c
new file mode 100644
index 0000000..5395843
--- /dev/null
+++ b/cli/src/compat/getopt.c
@@ -0,0 +1,66 @@
+/* Minimal POSIX getopt() for MSVC.
+   Supports short options with optional arguments (e.g., "d:"). */
+
+#include <stdio.h>
+#include <string.h>
+#include "include/msvc/getopt.h"
+
+char *optarg;
+int optind = 1, opterr = 1, optopt;
+
+int getopt(int argc, char *const argv[], const char *optstring)
+{
+	static int optpos = 0;
+
+	if (optind >= argc || !argv[optind])
+		return -1;
+
+	if (argv[optind][0] != '-' || !argv[optind][1])
+		return -1;
+
+	if (argv[optind][1] == '-' && !argv[optind][2]) {
+		optind++;
+		return -1;
+	}
+
+	if (!optpos)
+		optpos = 1;
+
+	int c = argv[optind][optpos];
+	const char *p = strchr(optstring, c);
+
+	if (!p || c == ':') {
+		optopt = c;
+		if (opterr && optstring[0] != ':')
+			fprintf(stderr, "%s: invalid option -- '%c'\n", argv[0], c);
+		if (!argv[optind][++optpos]) {
+			optind++;
+			optpos = 0;
+		}
+		return '?';
+	}
+
+	if (p[1] == ':') {
+		if (argv[optind][optpos + 1]) {
+			optarg = &argv[optind][optpos + 1];
+		} else if (++optind >= argc) {
+			optopt = c;
+			if (opterr && optstring[0] != ':')
+				fprintf(stderr, "%s: option requires an argument -- '%c'\n",
+				        argv[0], c);
+			optpos = 0;
+			return optstring[0] == ':' ? ':' : '?';
+		} else {
+			optarg = argv[optind];
+		}
+		optind++;
+		optpos = 0;
+	} else {
+		if (!argv[optind][++optpos]) {
+			optind++;
+			optpos = 0;
+		}
+	}
+
+	return c;
+}
diff --git a/cli/src/compat/include/err.h b/cli/src/compat/include/err.h
index 473d622..749e49d 100644
--- a/cli/src/compat/include/err.h
+++ b/cli/src/compat/include/err.h
@@ -2,7 +2,8 @@
 #define _ERR_H
 #ifdef __GNUC__
 #define err_noreturn __attribute__((noreturn))
-//#define err_noreturn [[noreturn]]
+#elif defined(_MSC_VER)
+#define err_noreturn __declspec(noreturn)
 #else
 #define err_noreturn
 #endif
diff --git a/cli/src/compat/include/msvc/getopt.h b/cli/src/compat/include/msvc/getopt.h
new file mode 100644
index 0000000..9766ed8
--- /dev/null
+++ b/cli/src/compat/include/msvc/getopt.h
@@ -0,0 +1,10 @@
+/* Minimal POSIX getopt for MSVC */
+#ifndef _COMPAT_GETOPT_H
+#define _COMPAT_GETOPT_H
+
+extern char *optarg;
+extern int optind, opterr, optopt;
+
+int getopt(int argc, char *const argv[], const char *optstring);
+
+#endif
diff --git a/cli/src/compat/include/msvc/unistd.h b/cli/src/compat/include/msvc/unistd.h
new file mode 100644
index 0000000..bd3fad4
--- /dev/null
+++ b/cli/src/compat/include/msvc/unistd.h
@@ -0,0 +1,32 @@
+/* Minimal POSIX unistd.h for MSVC */
+#ifndef _COMPAT_UNISTD_H
+#define _COMPAT_UNISTD_H
+
+#include <io.h>
+#include <direct.h>
+
+#ifndef F_OK
+#define F_OK 0
+#endif
+#ifndef R_OK
+#define R_OK 4
+#endif
+#ifndef W_OK
+#define W_OK 2
+#endif
+#ifndef X_OK
+#define X_OK 0
+#endif
+
+#ifndef PATH_MAX
+#define PATH_MAX 260
+#endif
+
+/* Provided by compat_win32.c (UTF-8-aware via wide-char APIs) */
+int access(const char *path, int mode);
+int unlink(const char *path);
+int chdir(const char *path);
+int mkdir(const char *path, int mode);
+int chmod(const char *path, int mode);
+
+#endif
diff --git a/cli/src/compat/include/msvc/utime.h b/cli/src/compat/include/msvc/utime.h
new file mode 100644
index 0000000..c5f5e91
--- /dev/null
+++ b/cli/src/compat/include/msvc/utime.h
@@ -0,0 +1,14 @@
+/* POSIX utime.h for MSVC (which only provides sys/utime.h) */
+#ifndef _COMPAT_UTIME_H
+#define _COMPAT_UTIME_H
+
+#include <time.h>
+
+struct utimbuf {
+	time_t actime;
+	time_t modtime;
+};
+
+int utime(const char *path, struct utimbuf *ut);
+
+#endif
diff --git a/cli/src/compat/include/sys/stat.h b/cli/src/compat/include/posix/sys/stat.h
similarity index 100%
rename from cli/src/compat/include/sys/stat.h
rename to cli/src/compat/include/posix/sys/stat.h
diff --git a/cli/src/compat/include/sys/utime.h b/cli/src/compat/include/posix/sys/utime.h
similarity index 100%
rename from cli/src/compat/include/sys/utime.h
rename to cli/src/compat/include/posix/sys/utime.h
diff --git a/cli/src/compat/include/unistd.h b/cli/src/compat/include/posix/unistd.h
similarity index 100%
rename from cli/src/compat/include/unistd.h
rename to cli/src/compat/include/posix/unistd.h
diff --git a/cmake/UC2Platform.cmake b/cmake/UC2Platform.cmake
index 7bb841b..2dd1999 100644
--- a/cmake/UC2Platform.cmake
+++ b/cmake/UC2Platform.cmake
@@ -8,4 +8,5 @@ if(CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
     endif()
 elseif(MSVC)
     add_compile_options(/W3)
+    add_compile_definitions(_CRT_SECURE_NO_WARNINGS)
 endif()