diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 55d6a64ee..cf7a74816 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,9 @@
+Fri Sep  7 10:27:00 2001  Corinna Vinschen <corinna@vinschen.de>
+
+	* include/limits.h: Define PIPE_BUF.
+	* syscalls.cc (fpathconf): Use PIPE_BUF instead of numerical constant.
+	(pathconf): Ditto.
+
 Thu Sep  6 20:04:05 2001  Christopher Faylor <cgf@cygnus.com>
 
 	* fhandler_socket.cc (fhandler_socket::fhandler_socket): Ensure that
diff --git a/winsup/cygwin/include/limits.h b/winsup/cygwin/include/limits.h
index 4a2ad3a8d..9eaac0b34 100644
--- a/winsup/cygwin/include/limits.h
+++ b/winsup/cygwin/include/limits.h
@@ -129,6 +129,11 @@ details. */
 #undef OPEN_MAX
 #define OPEN_MAX 256
 
+/* # of bytes in a pipe buf. This is the max # of bytes which can be
+   written to a pipe in one atomic operation. */
+#undef PIPE_BUF
+#define PIPE_BUF 4096
+
 /* POSIX values */
 /* These should never vary from one system type to another */
 /* They represent the minimum values that POSIX systems must support.
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 6f26e882e..5e5566a4b 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -1533,7 +1533,7 @@ fpathconf (int fd, int v)
     case _PC_PATH_MAX:
       return PATH_MAX;
     case _PC_PIPE_BUF:
-      return 4096;
+      return PIPE_BUF;
     case _PC_CHOWN_RESTRICTED:
     case _PC_NO_TRUNC:
       return -1;
@@ -1575,7 +1575,7 @@ pathconf (const char *file, int v)
     case _PC_MAX_INPUT:
       return _POSIX_MAX_CANON;
     case _PC_PIPE_BUF:
-      return 4096;
+      return PIPE_BUF;
     case _PC_CHOWN_RESTRICTED:
     case _PC_NO_TRUNC:
       return -1;