diff --git a/ChangeLog b/ChangeLog
index 687b51fdbe..064733dc2a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Nov 22 01:45:21 2005  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* file.c (rb_file_s_basename): DOSISH_UNC is defined on cygwin but
+	  DOSISH is not.  fixed: [ruby-dev:27797]
+
 Mon Nov 21 22:50:48 2005  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* file.c (rb_path_skip_prefix, rb_file_s_basename): UNC without path
diff --git a/file.c b/file.c
index 37c83f208a..57069cf3bb 100644
--- a/file.c
+++ b/file.c
@@ -2573,7 +2573,7 @@ rb_file_s_basename(int argc, VALUE *argv)
 {
     VALUE fname, fext, basename;
     char *name, *p;
-#ifdef DOSISH
+#if defined DOSISH_DRIVE_LETTER || defined DOSISH_UNC
     char *root;
 #endif
     int f;
@@ -2585,7 +2585,7 @@ rb_file_s_basename(int argc, VALUE *argv)
     if (RSTRING(fname)->len == 0 || !*(name = RSTRING(fname)->ptr))
 	return fname;
     name = skipprefix(name);
-#ifdef DOSISH
+#if defined DOSISH_DRIVE_LETTER || defined DOSISH_UNC
     root = name;
 #endif
     while (isdirsep(*name))
@@ -2593,7 +2593,7 @@ rb_file_s_basename(int argc, VALUE *argv)
     if (!*name) {
 	p = name - 1;
 	f = 1;
-#ifdef DOSISH
+#if defined DOSISH_DRIVE_LETTER || defined DOSISH_UNC
 	if (name != root) {
 	    /* has slashes */
 	}