diff --git a/src/lib9pclient/seek.c b/src/lib9pclient/seek.c
new file mode 100644
index 0000000..0785c4b
--- /dev/null
+++ b/src/lib9pclient/seek.c
@@ -0,0 +1,46 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <9pclient.h>
+#include "fsimpl.h"
+
+vlong
+fsseek(CFid *fid, vlong n, int whence)
+{
+	Dir *d;
+
+	switch(whence){
+	case 0:
+		qlock(&fid->lk);
+		fid->offset = n;
+		qunlock(&fid->lk);
+		break;
+	case 1:
+		qlock(&fid->lk);
+		n += fid->offset;
+		if(n < 0){
+			qunlock(&fid->lk);
+			werrstr("negative offset");
+			return -1;
+		}
+		fid->offset = n;
+		qunlock(&fid->lk);
+		break;
+	case 2:
+		if((d = fsdirfstat(fid)) == nil)
+			return -1;
+		n += d->length;
+		if(n < 0){
+			werrstr("negative offset");
+			return -1;
+		}
+		qlock(&fid->lk);
+		fid->offset = n;
+		qunlock(&fid->lk);
+		break;
+	default:
+		werrstr("bad whence in fsseek");
+		return -1;
+	}
+	return n;
+}