diff --git a/ChangeLog b/ChangeLog
index ac46654a75..347db71c7e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Thu Nov 11 21:24:36 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* file.c (file_expand_path): use cygwin_conv_path on cygwin 1.7 or
+	  later.
+
+	* ruby.c (push_include_cygwin): ditto.
+
 Thu Nov 11 20:49:48 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* include/ruby/ruby.h (PRI_LL_PREFIX): format type specifier for
diff --git a/configure.in b/configure.in
index 3346a91194..8f5bc1d54f 100644
--- a/configure.in
+++ b/configure.in
@@ -989,6 +989,7 @@ main()
 		LIBS="$LIBS" # m lib is include in root under BeOS/Haiku
 		],
 [cygwin*], [	ac_cv_header_langinfo_h=yes
+		AC_CHECK_FUNCS(cygwin_conv_path)
 		AC_LIBOBJ([langinfo])
 		],
 [mingw*], [	LIBS="-lshell32 -lws2_32 -limagehlp $LIBS"
diff --git a/file.c b/file.c
index 9cca3d01b7..dc9f830fc7 100644
--- a/file.c
+++ b/file.c
@@ -3088,26 +3088,47 @@ file_expand_path(VALUE fname, VALUE dname, int abs_mode, VALUE result)
 	size_t len;
 	WIN32_FIND_DATA wfd;
 #ifdef __CYGWIN__
+	ssize_t bufsize;
 	int lnk_added = 0, is_symlink = 0;
 	struct stat st;
-	char w32buf[MAXPATHLEN];
 	p = (char *)s;
+	len = strlen(p);
 	if (lstat(buf, &st) == 0 && S_ISLNK(st.st_mode)) {
 	    is_symlink = 1;
-	    *p = '\0';
-	}
-	if (cygwin_conv_to_win32_path((*buf ? buf : "/"), w32buf) == 0) {
-	    b = w32buf;
-	}
-	if (is_symlink && b == w32buf) {
-	    *p = '\\';
-	    strlcat(w32buf, p, sizeof(w32buf));
-	    len = strlen(p);
 	    if (len > 4 && STRCASECMP(p + len - 4, ".lnk") != 0) {
 		lnk_added = 1;
-		strlcat(w32buf, ".lnk", sizeof(w32buf));
 	    }
 	}
+	const char *path = *buf ? buf : "/";
+#ifdef HAVE_CYGWIN_CONV_PATH
+	char *w32buf = NULL;
+	const int flags = CCP_POSIX_TO_WIN_A | CCP_RELATIVE;
+	bufsize = cygwin_conv_path(flags, path, NULL, 0);
+	if (bufsize > 0) {
+	    bufsize += len;
+	    if (lnk_added) bufsize += 4;
+	    w32buf = ALLOCA_N(char, bufsize);
+	    if (cygwin_conv_path(flags, path, w32buf, bufsize) == 0) {
+		b = w32buf;
+	    }
+	}
+#else
+	char w32buf[MAXPATHLEN];
+	bufsize = MAXPATHLEN;
+	if (cygwin_conv_to_win32_path(path, w32buf) == 0) {
+	    b = w32buf;
+	}
+#endif
+	if (is_symlink && b == w32buf) {
+	    *p = '\\';
+	    strlcat(w32buf, p, bufsize);
+	    if (lnk_added) {
+		strlcat(w32buf, ".lnk", bufsize);
+	    }
+	}
+	else {
+	    lnk_added = 0;
+	}
 	*p = '/';
 #endif
 	HANDLE h = FindFirstFile(b, &wfd);
diff --git a/ruby.c b/ruby.c
index 61e8dcc443..ecce05afe4 100644
--- a/ruby.c
+++ b/ruby.c
@@ -255,7 +255,14 @@ push_include_cygwin(const char *path, VALUE (*filter)(VALUE))
 		p = strncpy(RSTRING_PTR(buf), p, len);
 	    }
 	}
-	if (cygwin_conv_to_posix_path(p, rubylib) == 0)
+#ifdef HAVE_CYGWIN_CONV_PATH
+#define CONV_TO_POSIX_PATH(p, lib) \
+	cygwin_conv_path(CCP_WIN_A_TO_POSIX|CCP_RELATIVE, p, lib, sizeof(lib))
+#else
+#define CONV_TO_POSIX_PATH(p, lib) \
+	cygwin_conv_to_posix_path(p, lib)
+#endif
+	if (CONV_TO_POSIX_PATH(p, rubylib) == 0)
 	    p = rubylib;
 	push_include(p, filter);
 	if (!*s) break;
@@ -343,7 +350,7 @@ ruby_init_loadpath_safe(int safe_level)
     extern const char ruby_initial_load_paths[];
     const char *paths = ruby_initial_load_paths;
 #if defined LOAD_RELATIVE
-# if defined HAVE_DLADDR || (defined __CYGWIN__ && defined CCP_WIN_A_TO_POSIX)
+# if defined HAVE_DLADDR || defined HAVE_CYGWIN_CONV_PATH
 #   define VARIABLE_LIBPATH 1
 # else
 #   define VARIABLE_LIBPATH 0