diff --git a/ChangeLog b/ChangeLog
index 6a55f98..f5930b1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,10 @@
 Version 1.6.11
 *******************************************************************************
 
+2011-01-16 Marcelo Roberto Jimenez <mroberto(at)users.sourceforge.net>
+
+	Use config.h to test for the availability of strndup() and strnlen().
+
 2011-01-14 Chandra Penke <chandrapenke(at)mcntech.com>
 
 	- Null termination of strndup() implementation on systems missing it.
diff --git a/build/inc/autoconfig.h b/build/inc/autoconfig.h
index 04e10e8..363a24b 100644
--- a/build/inc/autoconfig.h
+++ b/build/inc/autoconfig.h
@@ -49,6 +49,12 @@
 /* Define to 1 if you have the <string.h> header file. */
 #define HAVE_STRING_H 1
 
+/* Defines if strndup is available on your system */
+#define HAVE_STRNDUP 1
+
+/* Defines if strnlen is available on your system */
+#define HAVE_STRNLEN 1
+
 /* Define to 1 if you have the <syslog.h> header file. */
 #define HAVE_SYSLOG_H 1
 
diff --git a/configure.ac b/configure.ac
index d9858fd..03c68ba 100644
--- a/configure.ac
+++ b/configure.ac
@@ -497,6 +497,10 @@ fi
 #
 AC_FUNC_VPRINTF
 AC_FUNC_FSEEKO
+AC_CHECK_FUNC(strnlen,
+	AC_DEFINE(HAVE_STRNLEN, 1, [Defines if strnlen is available on your system]))
+AC_CHECK_FUNC(strndup,
+	AC_DEFINE(HAVE_STRNDUP, 1, [Defines if strndup is available on your system]))
 #
 # Solaris needs -lsocket -lnsl -lrt
 AC_SEARCH_LIBS([bind],           [socket])
diff --git a/upnp/src/api/UpnpString.c b/upnp/src/api/UpnpString.c
index e29fbf4..f3b069e 100644
--- a/upnp/src/api/UpnpString.c
+++ b/upnp/src/api/UpnpString.c
@@ -28,20 +28,21 @@
 	/* Other systems have strncasecmp */
 #endif
 
-/* strndup() is a GNU extension. Other systems must fix it with elif's. */
-#if defined(__GNUC__) && !defined(__APPLE__)
-	extern char *strndup(__const char *__string, size_t __n);
-#endif /* defined(__GNUC__) && !defined(__APPLE__) */
-
-#if defined(__GNUC__) && defined(__APPLE__)
+/* strnlen() is a GNU extension. */
+#if HAVE_STRNLEN
+	extern size_t strnlen(const char *s, size_t maxlen);
+#else /* HAVE_STRNLEN */
 	static size_t strnlen(const char *s, size_t n)
 	{
 		const char *p = (const char *)memchr(s, 0, n);
 		return p ? p - s : n;
 	}
-#endif /* defined(__GNUC__) && defined(__APPLE__) */
+#endif /* HAVE_STRNLEN */
 
-#if (defined(__GNUC__) && defined(__APPLE__)) || defined(WIN32)
+/* strndup() is a GNU extension. */
+#if HAVE_STRNDUP && !defined(WIN32)
+	extern char *strndup(__const char *__string, size_t __n);
+#else /* HAVE_STRNDUP && !defined(WIN32) */
 	static char *strndup(const char *__string, size_t __n)
 	{
 		size_t strsize = strnlen(__string, __n);
@@ -52,7 +53,7 @@
 
 		return newstr;
 	}
-#endif /* (defined(__GNUC__) && defined(__APPLE__)) || defined(WIN32) */
+#endif /* HAVE_STRNDUP && !defined(WIN32) */
 
 /*!
  * \brief Internal implementation of the class UpnpString.