diff --git a/compat/mingw.c b/compat/mingw.c
index 6accd26f2a..9891950d4e 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -3625,7 +3625,7 @@ int xwcstoutf(char *utf, const wchar_t *wcs, size_t utflen)
 }
 
 #ifdef ENSURE_MSYSTEM_IS_SET
-#if !defined(RUNTIME_PREFIX) || !defined(HAVE_WPGMPTR)
+#if !defined(RUNTIME_PREFIX) || !defined(HAVE_WPGMPTR) || !defined(MINGW_PREFIX)
 static size_t append_system_bin_dirs(char *path UNUSED, size_t size UNUSED)
 {
 	return 0;
@@ -3643,25 +3643,16 @@ static size_t append_system_bin_dirs(char *path, size_t size)
 	/* strip trailing `git.exe` */
 	len = slash - prefix;
 
-	/* strip trailing `cmd` or `mingw64\bin` or `mingw32\bin` or `bin` or `libexec\git-core` */
-	if (strip_suffix_mem(prefix, &len, "\\mingw64\\libexec\\git-core") ||
-	    strip_suffix_mem(prefix, &len, "\\mingw64\\bin"))
+	/* strip trailing `cmd` or `<mingw-prefix>\bin` or `bin` or `libexec\git-core` */
+	if (strip_suffix_mem(prefix, &len, "\\" MINGW_PREFIX "\\libexec\\git-core") ||
+	    strip_suffix_mem(prefix, &len, "\\" MINGW_PREFIX "\\bin"))
 		off += xsnprintf(path + off, size - off,
-				 "%.*s\\mingw64\\bin;", (int)len, prefix);
-	else if (strip_suffix_mem(prefix, &len, "\\clangarm64\\libexec\\git-core") ||
-	    strip_suffix_mem(prefix, &len, "\\clangarm64\\bin"))
-		off += xsnprintf(path + off, size - off,
-				 "%.*s\\clangarm64\\bin;", (int)len, prefix);
-	else if (strip_suffix_mem(prefix, &len, "\\mingw32\\libexec\\git-core") ||
-		 strip_suffix_mem(prefix, &len, "\\mingw32\\bin"))
-		off += xsnprintf(path + off, size - off,
-				 "%.*s\\mingw32\\bin;", (int)len, prefix);
+				 "%.*s\\" MINGW_PREFIX "\\bin;", (int)len, prefix);
 	else if (strip_suffix_mem(prefix, &len, "\\cmd") ||
 		 strip_suffix_mem(prefix, &len, "\\bin") ||
 		 strip_suffix_mem(prefix, &len, "\\libexec\\git-core"))
 		off += xsnprintf(path + off, size - off,
-				 "%.*s\\mingw%d\\bin;", (int)len, prefix,
-				 (int)(sizeof(void *) * 8));
+				 "%.*s\\" MINGW_PREFIX "\\bin;", (int)len, prefix);
 	else
 		return 0;
 
@@ -3757,13 +3748,7 @@ static void setup_windows_environment(void)
 		char buf[32768];
 		size_t off = 0;
 
-#if defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
-		setenv("MSYSTEM", "CLANGARM64", 1);
-#elif defined(__MINGW64__) || defined(_M_AMD64)
-		setenv("MSYSTEM", "MINGW64", 1);
-#else
-		setenv("MSYSTEM", "MINGW32", 1);
-#endif
+		setenv("MSYSTEM", ENSURE_MSYSTEM_IS_SET, 1);
 
 		if (home)
 			off += xsnprintf(buf + off, sizeof(buf) - off,
diff --git a/config.mak.uname b/config.mak.uname
index 289ded45c7..1c8a32b2b1 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -452,14 +452,8 @@ ifeq ($(uname_S),Windows)
 	GIT_VERSION := $(GIT_VERSION).MSVC
 	pathsep = ;
 	# Assume that this is built in Git for Windows' SDK
-        ifeq (MINGW32,$(MSYSTEM))
-		prefix = /mingw32
-        else
-                ifeq (CLANGARM64,$(MSYSTEM))
-			prefix = /clangarm64
-                else
-			prefix = /mingw64
-                endif
+        ifneq (,$(MSYSTEM))
+		prefix = $(MINGW_PREFIX)
         endif
 	# Prepend MSVC 64-bit tool-chain to PATH.
 	#
@@ -529,7 +523,9 @@ endif
 		compat/win32/pthread.o compat/win32/syslog.o \
 		compat/win32/trace2_win32_process_info.o \
 		compat/win32/dirent.o compat/win32/fscache.o compat/win32/wsl.o
-	COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DDETECT_MSYS_TTY -DENSURE_MSYSTEM_IS_SET -DNOGDI -DHAVE_STRING_H -Icompat -Icompat/regex -Icompat/win32 -DSTRIP_EXTENSION=\".exe\"
+	COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DDETECT_MSYS_TTY \
+		-DENSURE_MSYSTEM_IS_SET="\"$(MSYSTEM)\"" -DMINGW_PREFIX="\"$(patsubst /%,%,$(MINGW_PREFIX))\"" \
+		-DNOGDI -DHAVE_STRING_H -Icompat -Icompat/regex -Icompat/win32 -DSTRIP_EXTENSION=\".exe\"
 	BASIC_LDFLAGS = -IGNORE:4217 -IGNORE:4049 -NOLOGO
 	# invalidcontinue.obj allows Git's source code to close the same file
 	# handle twice, or to access the osfhandle of an already-closed stdout
@@ -748,10 +744,16 @@ ifeq ($(uname_S),MINGW)
 		BASIC_LDFLAGS += -Wl,--dynamicbase
         endif
         ifneq (,$(MSYSTEM))
+                ifeq ($(MINGW_PREFIX),$(filter-out /%,$(MINGW_PREFIX)))
+			# Override if empty or does not start with a slash
+			MINGW_PREFIX := /$(shell echo '$(MSYSTEM)' | tr A-Z a-z)
+                endif
 		prefix = $(MINGW_PREFIX)
 		HOST_CPU = $(patsubst %-w64-mingw32,%,$(MINGW_CHOST))
 		BASIC_LDFLAGS += -Wl,--pic-executable
-		COMPAT_CFLAGS += -DDETECT_MSYS_TTY -DENSURE_MSYSTEM_IS_SET
+		COMPAT_CFLAGS += -DDETECT_MSYS_TTY \
+			-DENSURE_MSYSTEM_IS_SET="\"$(MSYSTEM)\"" \
+			-DMINGW_PREFIX="\"$(patsubst /%,%,$(MINGW_PREFIX))\""
                 ifeq (MINGW32,$(MSYSTEM))
 			BASIC_LDFLAGS += -Wl,--large-address-aware
                 endif
diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt
index 6443dfbac5..c69f3a7ea9 100644
--- a/contrib/buildsystems/CMakeLists.txt
+++ b/contrib/buildsystems/CMakeLists.txt
@@ -282,7 +282,14 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
 				_CONSOLE DETECT_MSYS_TTY STRIP_EXTENSION=".exe"  NO_SYMLINK_HEAD UNRELIABLE_FSTAT
 				NOGDI OBJECT_CREATION_MODE=1 __USE_MINGW_ANSI_STDIO=0
 				USE_NED_ALLOCATOR OVERRIDE_STRDUP MMAP_PREVENTS_DELETE USE_WIN32_MMAP
-				HAVE_WPGMPTR ENSURE_MSYSTEM_IS_SET HAVE_RTLGENRANDOM)
+				HAVE_WPGMPTR HAVE_RTLGENRANDOM)
+	if(CMAKE_GENERATOR_PLATFORM STREQUAL "x64")
+		add_compile_definitions(ENSURE_MSYSTEM_IS_SET="MINGW64" MINGW_PREFIX="mingw64")
+	elseif(CMAKE_GENERATOR_PLATFORM STREQUAL "arm64")
+		add_compile_definitions(ENSURE_MSYSTEM_IS_SET="CLANGARM64" MINGW_PREFIX="clangarm64")
+	elseif(CMAKE_GENERATOR_PLATFORM STREQUAL "x86")
+		add_compile_definitions(ENSURE_MSYSTEM_IS_SET="MINGW32" MINGW_PREFIX="mingw32")
+	endif()
 	list(APPEND compat_SOURCES
 		compat/mingw.c
 		compat/winansi.c
diff --git a/meson.build b/meson.build
index 46b1369c45..03fa16012d 100644
--- a/meson.build
+++ b/meson.build
@@ -1271,7 +1271,6 @@ elif host_machine.system() == 'windows'
 
   libgit_c_args += [
     '-DDETECT_MSYS_TTY',
-    '-DENSURE_MSYSTEM_IS_SET',
     '-DNATIVE_CRLF',
     '-DNOGDI',
     '-DNO_POSIX_GOODIES',
@@ -1281,6 +1280,18 @@ elif host_machine.system() == 'windows'
     '-D__USE_MINGW_ANSI_STDIO=0',
   ]
 
+  msystem = get_option('msystem')
+  if msystem != ''
+    mingw_prefix = get_option('mingw_prefix')
+    if mingw_prefix == ''
+      mingw_prefix = '/' + msystem.to_lower()
+    endif
+    libgit_c_args += [
+      '-DENSURE_MSYSTEM_IS_SET="' + msystem + '"',
+      '-DMINGW_PREFIX="' + mingw_prefix + '"'
+    ]
+  endif
+
   libgit_dependencies += compiler.find_library('ntdll')
   libgit_include_directories += 'compat/win32'
   if compiler.get_id() == 'msvc'
diff --git a/meson_options.txt b/meson_options.txt
index e0be260ae1..c2d9f0bfc0 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -21,6 +21,10 @@ option('runtime_prefix', type: 'boolean', value: false,
   description: 'Resolve ancillary tooling and support files relative to the location of the runtime binary instead of hard-coding them into the binary.')
 option('sane_tool_path', type: 'array', value: [],
   description: 'An array of paths to pick up tools from in case the normal tools are broken or lacking.')
+option('msystem', type: 'string', value: '',
+  description: 'Fall-back on Windows when MSYSTEM is not set.')
+option('mingw_prefix', type: 'string', value: '',
+  description: 'Fall-back on Windows when MINGW_PREFIX is not set.')
 
 # Build information compiled into Git and other parts like documentation.
 option('build_date', type: 'string', value: '',