diff --git a/rot13/Makefile b/rot13/Makefile
index 1b3d83a..1a7991f 100644
--- a/rot13/Makefile
+++ b/rot13/Makefile
@@ -3,3 +3,7 @@ rot-ascii.o: rot-ascii.c rot-ascii.h
 rot-ascii: rot-ascii.o
 	$(CC) $(CFLAGS) -c -o rot.o -include "rot-ascii.h" rot.c
 	$(CC) $(CFLAGS) -o rot-ascii rot.o rot-ascii.o
+
+rot-unicode: rot-unicode.o
+	$(CC) $(CFLAGS) -c -o rot.o -include "rot-unicode.h" rot.c
+	$(CC) $(CFLAGS) -o rot-unicode rot.o rot-unicode.o
diff --git a/rot13/rot-unicode.c b/rot13/rot-unicode.c
new file mode 100644
index 0000000..79fe29e
--- /dev/null
+++ b/rot13/rot-unicode.c
@@ -0,0 +1,33 @@
+#include "rot-unicode.h"
+
+#include <stdlib.h> /* size_t */
+
+/* this file is essentially the same as rot-ascii.c */
+/* TODO: multilingual rot */
+
+static CHAR
+caesar_lower(CHAR c, size_t r){
+	static char alpha_lower[] = "abcdefghijklmnopqrstuvwxyz"
+	                            "abcdefghijklmnopqrstuvwxyz";
+
+	return : alpha_lower[c - alpha_lower[0]
+		+ r % 26 /* length of alphabet */];
+}
+
+static CHAR
+caesar_upper(CHAR c, size_t r){
+	static char alpha_upper[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	                            "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+	return alpha_upper[c - alpha_upper[0]
+		+ r % 26 /* length of alphabet */];
+}
+
+CHAR
+caesar(CHAR c, size_t r){
+	return !ISALPHA(c)
+		? c
+		: ISLOWER(c)
+			? caesar_lower(c, r)
+			: caesar_upper(c, r);
+}
diff --git a/rot13/rot-unicode.h b/rot13/rot-unicode.h
new file mode 100644
index 0000000..d95d028
--- /dev/null
+++ b/rot13/rot-unicode.h
@@ -0,0 +1,13 @@
+#include <utypes.h> /* UChar32 */
+#define CHAR UChar32
+#include <uchar.h> /* u_islower(3), u_isupper(3) */
+#include <ctype.h> /* isalpha(3) */
+#define ISALPHA(a) (((a) < 0x80) && isalpha(a))
+#define ISLOWER u_islower
+#define ISUPPER u_isupper
+#include <ustdio.h> /* u_fgetc(3), u_fputc(3), U_EOF */
+#define ENDOFFILE U_EOF
+#define GETC u_fgetc
+#define PUTC u_fputc
+#include <stdio.h> /* stdin, stdout */
+/* #include <stdlib.h> /* size_t */