diff --git a/include/libString.h b/include/libString.h
new file mode 100644
index 0000000..d848706
--- /dev/null
+++ b/include/libString.h
@@ -0,0 +1,46 @@
+/*
+#pragma	src	"/sys/src/libString"
+#pragma	lib	"libString.a"
+*/
+
+/* extensible Strings */
+typedef struct String {
+	Lock	lk;
+	char	*base;	/* base of String */
+	char	*end;	/* end of allocated space+1 */
+	char	*ptr;	/* ptr into String */
+	short	ref;
+	uchar	fixed;
+} String;
+
+#define s_clone(s) s_copy((s)->base)
+#define s_to_c(s) ((s)->base)
+#define s_len(s) ((s)->ptr-(s)->base)
+
+extern String*	s_append(String*, char*);
+extern String*	s_array(char*, int);
+extern String*	s_copy(char*);
+extern void	s_free(String*);
+extern String*	s_incref(String*);	
+extern String*	s_memappend(String*, char*, int);
+extern String*	s_nappend(String*, char*, int);
+extern String*	s_new(void);
+extern String*	s_newalloc(int);
+extern String*	s_parse(String*, String*);
+extern String*	s_reset(String*);
+extern String*	s_restart(String*);
+extern void	s_terminate(String*);
+extern void	s_tolower(String*);
+extern void	s_putc(String*, int);
+extern String*	s_unique(String*);
+extern String*	s_grow(String*, int);
+
+#ifdef BGETC
+extern int	s_read(Biobuf*, String*, int);
+extern char	*s_read_line(Biobuf*, String*);
+extern char	*s_getline(Biobuf*, String*);
+typedef struct Sinstack Sinstack;
+extern char	*s_rdinstack(Sinstack*, String*);
+extern Sinstack	*s_allocinstack(char*);
+extern void	s_freeinstack(Sinstack*);
+#endif BGETC