diff --git a/compat/mingw.c b/compat/mingw.c
index 96d9ac4eb7ffdc..786e456a50228d 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -6,9 +6,18 @@
 #include "../run-command.h"
 #include "../cache.h"
 
+#undef MAX_PATH
+#define MAX_PATH PATH_MAX
+
 static const int delay[] = { 0, 1, 10, 20, 40 };
 unsigned int _CRT_fmode = _O_BINARY;
 
+static wchar_t * deprefix(wchar_t *path) {
+	if ( path && wcsncmp(path, L"\\\\?\\", 4) == 0 )
+		return path + 4;
+	return path;
+}
+
 int err_win_to_posix(DWORD winerr)
 {
 	int error = ENOSYS;
@@ -337,11 +346,11 @@ int mingw_open (const char *filename, int oflags, ...)
 	mode = va_arg(args, int);
 	va_end(args);
 
-	if (filename && !strcmp(filename, "/dev/null"))
-		filename = "nul";
-
-	if (xutftowcs_path(wfilename, filename) < 0)
+	if (filename && !strcmp(filename, "/dev/null")) {
+		wcscpy(wfilename, L"nul\0");
+	} else if (xutftowcs_path(wfilename, filename) < 0) {
 		return -1;
+	}
 	fd = _wopen(wfilename, oflags, mode);
 
 	if (fd < 0 && (oflags & O_CREAT) && errno == EACCES) {
@@ -414,11 +423,15 @@ FILE *mingw_fopen (const char *filename, const char *otype)
 	if (hide_dotfiles == HIDE_DOTFILES_TRUE &&
 	    basename((char*)filename)[0] == '.')
 		hide = access(filename, F_OK);
-	if (filename && !strcmp(filename, "/dev/null"))
-		filename = "nul";
-	if (xutftowcs_path(wfilename, filename) < 0 ||
-		xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0)
+	if (filename && !strcmp(filename, "/dev/null"))  {
+		wcscpy(wfilename, L"nul\0");
+	} else if (xutftowcs_path(wfilename, filename) < 0) {
+		return NULL;
+	}
+
+	if (xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0) {
 		return NULL;
+	}
 	file = _wfopen(wfilename, wotype);
 	if (file && hide && make_hidden(wfilename))
 		warning("Could not mark '%s' as hidden.", filename);
@@ -433,11 +446,15 @@ FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream)
 	if (hide_dotfiles == HIDE_DOTFILES_TRUE &&
 	    basename((char*)filename)[0] == '.')
 		hide = access(filename, F_OK);
-	if (filename && !strcmp(filename, "/dev/null"))
-		filename = "nul";
-	if (xutftowcs_path(wfilename, filename) < 0 ||
-		xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0)
+	if (filename && !strcmp(filename, "/dev/null"))  {
+		wcscpy(wfilename, L"nul\0");
+	} else if (xutftowcs_path(wfilename, filename) < 0) {
+		return NULL;
+	}
+
+	if (xutftowcs(wotype, otype, ARRAY_SIZE(wotype)) < 0) {
 		return NULL;
+	}
 	file = _wfreopen(wfilename, wotype, stream);
 	if (file && hide && make_hidden(wfilename))
 		warning("Could not mark '%s' as hidden.", filename);
@@ -480,7 +497,7 @@ int mingw_chdir(const char *dirname)
 	wchar_t wdirname[MAX_PATH];
 	if (xutftowcs_path(wdirname, dirname) < 0)
 		return -1;
-	return _wchdir(wdirname);
+	return _wchdir(deprefix(wdirname));
 }
 
 int mingw_chmod(const char *filename, int mode)
@@ -709,12 +726,20 @@ unsigned int sleep (unsigned int seconds)
 char *mingw_mktemp(char *template)
 {
 	wchar_t wtemplate[MAX_PATH];
+	char template_abspath[MAX_PATH];
 	if (xutftowcs_path(wtemplate, template) < 0)
 		return NULL;
 	if (!_wmktemp(wtemplate))
 		return NULL;
-	if (xwcstoutf(template, wtemplate, strlen(template) + 1) < 0)
+	if (xwcstoutf(template_abspath, deprefix(wtemplate), sizeof(template_abspath)) < 0)
 		return NULL;
+	/* copy only the base name name back to the template */
+	int idxt = strlen(template);
+	int idxtabs = strlen(template_abspath);
+	int len = strlen(basename(template));
+	for (; len >= 0; len--) {
+		template[idxt--] = template_abspath[idxtabs--];
+	}
 	return template;
 }
 
@@ -782,7 +807,7 @@ char *mingw_getcwd(char *pointer, int len)
 	wchar_t wpointer[MAX_PATH];
 	if (!_wgetcwd(wpointer, ARRAY_SIZE(wpointer)))
 		return NULL;
-	if (xwcstoutf(pointer, wpointer, len) < 0)
+	if (xwcstoutf(pointer, deprefix(wpointer), len) < 0)
 		return NULL;
 	for (i = 0; pointer[i]; i++)
 		if (pointer[i] == '\\')
@@ -1180,7 +1205,7 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 	wenvblk = make_environment_block(deltaenv);
 
 	memset(&pi, 0, sizeof(pi));
-	ret = CreateProcessW(wcmd, wargs, NULL, NULL, TRUE, flags,
+	ret = CreateProcessW(deprefix(wcmd), wargs, NULL, NULL, TRUE, flags,
 		wenvblk, dir ? wdir : NULL, &si, &pi);
 
 	free(wenvblk);
diff --git a/compat/mingw.h b/compat/mingw.h
index 8848c7bc2c5d05..7e75f9e2096e7a 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -4,6 +4,8 @@
 /*
  * things that are not available in header files
  */
+#undef PATH_MAX
+#define PATH_MAX 4096
 
 typedef int pid_t;
 typedef int uid_t;
@@ -405,10 +407,29 @@ static inline int xutftowcs(wchar_t *wcs, const char *utf, size_t wcslen)
  */
 static inline int xutftowcs_path(wchar_t *wcs, const char *utf)
 {
-	int result = xutftowcsn(wcs, utf, MAX_PATH, -1);
-	if (result < 0 && errno == ERANGE)
+	wchar_t buf[PATH_MAX - 4];
+
+	if (!strcmp(utf, "nul")) {
+		/* don't prefix reserved file name 'nul' */
+		memcpy(wcs, &(L"nul\0"), sizeof(buf));
+		return 3;
+	}
+
+	int result = xutftowcsn(wcs, utf, PATH_MAX - 4, -1);
+	if (result < 0 && errno == ERANGE) {
 		errno = ENAMETOOLONG;
-	return result;
+		return result;
+	}
+
+	result = GetFullPathNameW(wcs, PATH_MAX - 4, buf, NULL);
+	if (wcsncmp(buf, L"\\\\?\\", 4) == 0) {
+		memcpy(wcs, buf, sizeof(buf));
+		return result;
+	}
+
+	wcscpy(wcs, L"\\\\?\\");
+	memcpy(wcs + 4, buf, sizeof(buf));
+	return result + 4;
 }
 
 /**
diff --git a/compat/win32/dirent.c b/compat/win32/dirent.c
index 52420ec7d4dad7..0761cad249fb5e 100644
--- a/compat/win32/dirent.c
+++ b/compat/win32/dirent.c
@@ -32,7 +32,7 @@ DIR *opendir(const char *name)
 
 	/* append optional '/' and wildcard '*' */
 	if (len && !is_dir_sep(pattern[len - 1]))
-		pattern[len++] = '/';
+		pattern[len++] = '\\';
 	pattern[len++] = '*';
 	pattern[len] = 0;
 
diff --git a/compat/win32/dirent.h b/compat/win32/dirent.h
index 058207e4bfed62..575eaf7fd152d6 100644
--- a/compat/win32/dirent.h
+++ b/compat/win32/dirent.h
@@ -1,6 +1,9 @@
 #ifndef DIRENT_H
 #define DIRENT_H
 
+#undef MAX_PATH
+#define MAX_PATH 4096
+
 typedef struct DIR DIR;
 
 #define DT_UNKNOWN 0