Index: uspace/lib/posix/Makefile
===================================================================
--- uspace/lib/posix/Makefile	(revision a16210b5f6e79f95749bdd630e0d5c77f8f6c253)
+++ uspace/lib/posix/Makefile	(revision 0e89c28b6512f8a249f743a9d4efdcff08533305)
@@ -39,4 +39,5 @@
 
 SOURCES = \
+	ctype.c \
 	stdlib.c \
 	string.c \
Index: uspace/lib/posix/ctype.c
===================================================================
--- uspace/lib/posix/ctype.c	(revision 0e89c28b6512f8a249f743a9d4efdcff08533305)
+++ uspace/lib/posix/ctype.c	(revision 0e89c28b6512f8a249f743a9d4efdcff08533305)
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2011 Jiri Zarevucky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "ctype.h"
+
+int isxdigit(int ch)
+{
+	return isdigit(ch) ||
+	       (ch >= 'a' && ch <= 'f') ||
+	       (ch >= 'A' && ch <= 'F');
+}
+
Index: uspace/lib/posix/ctype.h
===================================================================
--- uspace/lib/posix/ctype.h	(revision 0e89c28b6512f8a249f743a9d4efdcff08533305)
+++ uspace/lib/posix/ctype.h	(revision 0e89c28b6512f8a249f743a9d4efdcff08533305)
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2011 Jiri Zarevucky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef POSIX_CTYPE_H_
+#define POSIX_CTYPE_H_
+
+#include "libc/ctype.h"
+
+extern int isxdigit(int ch);
+
+#endif /* POSIX_CTYPE_H_ */
+