diff --git a/include/ctype.h b/include/ctype.h
new file mode 100644
index 0000000..7acf55d
--- /dev/null
+++ b/include/ctype.h
@@ -0,0 +1,34 @@
+#ifndef _CTYPE_H
+#define _CTYPE_H
+
+#define _U	0x01	/* upper */
+#define _L	0x02	/* lower */
+#define _D	0x04	/* digit */
+#define _C	0x08	/* cntrl */
+#define _P	0x10	/* punct */
+#define _S	0x20	/* white space (space/lf/tab) */
+#define _X	0x40	/* hex digit */
+#define _SP	0x80	/* hard space (0x20) */
+
+extern unsigned char _ctype[];
+extern char _ctmp;
+
+#define isalnum(c) ((_ctype+1)[c]&(_U|_L|_D))
+#define isalpha(c) ((_ctype+1)[c]&(_U|_L))
+#define iscntrl(c) ((_ctype+1)[c]&(_C))
+#define isdigit(c) ((_ctype+1)[c]&(_D))
+#define isgraph(c) ((_ctype+1)[c]&(_P|_U|_L|_D))
+#define islower(c) ((_ctype+1)[c]&(_L))
+#define isprint(c) ((_ctype+1)[c]&(_P|_U|_L|_D|_SP))
+#define ispunct(c) ((_ctype+1)[c]&(_P))
+#define isspace(c) ((_ctype+1)[c]&(_S))
+#define isupper(c) ((_ctype+1)[c]&(_U))
+#define isxdigit(c) ((_ctype+1)[c]&(_D|_X))
+
+#define isascii(c) (((unsigned) c)<=0x7f)
+#define toascii(c) (((unsigned) c)&0x7f)
+
+#define tolower(c) (_ctmp=c,isupper(_ctmp)?_ctmp-('A'-'a'):_ctmp)
+#define toupper(c) (_ctmp=c,islower(_ctmp)?_ctmp-('a'-'A'):_ctmp)
+
+#endif