Index: uspace/lib/posix/include/posix/stdio.h
===================================================================
--- uspace/lib/posix/include/posix/stdio.h	(revision ccdc63e559f32b50f2381110a99211f6ed0775f3)
+++ uspace/lib/posix/include/posix/stdio.h	(revision e3480d5412afdfabbc3498e0ae4532b6f1d0a749)
@@ -65,7 +65,4 @@
 
 #define BUFSIZ  4096
-#define SEEK_SET  0
-#define SEEK_CUR  1
-#define SEEK_END  2
 
 typedef struct _IO_FILE FILE;
Index: uspace/lib/posix/include/posix/unistd.h
===================================================================
--- uspace/lib/posix/include/posix/unistd.h	(revision ccdc63e559f32b50f2381110a99211f6ed0775f3)
+++ uspace/lib/posix/include/posix/unistd.h	(revision e3480d5412afdfabbc3498e0ae4532b6f1d0a749)
@@ -44,4 +44,8 @@
 #include "stddef.h"
 
+#define SEEK_SET  0
+#define SEEK_CUR  1
+#define SEEK_END  2
+
 /* Process Termination */
 #define _exit exit
@@ -77,4 +81,6 @@
 extern ssize_t __POSIX_DEF__(read)(int fildes, void *buf, size_t nbyte);
 extern ssize_t __POSIX_DEF__(write)(int fildes, const void *buf, size_t nbyte);
+extern __POSIX_DEF__(off_t) __POSIX_DEF__(lseek)(int fildes,
+    __POSIX_DEF__(off_t) offset, int whence);
 extern int __POSIX_DEF__(fsync)(int fildes);
 extern int __POSIX_DEF__(ftruncate)(int fildes, __POSIX_DEF__(off_t) length);
Index: uspace/lib/posix/source/unistd.c
===================================================================
--- uspace/lib/posix/source/unistd.c	(revision ccdc63e559f32b50f2381110a99211f6ed0775f3)
+++ uspace/lib/posix/source/unistd.c	(revision e3480d5412afdfabbc3498e0ae4532b6f1d0a749)
@@ -221,4 +221,16 @@
 {
 	return errnify(write, fildes, buf, nbyte);
+}
+
+/**
+ * Reposition read/write file offset
+ *
+ * @param fildes File descriptor of the opened file.
+ * @return Upon successful completion, returns the resulting offset
+ *         as measured in bytes from the beginning of the file, -1 otherwise.
+ */
+posix_off_t posix_lseek(int fildes, posix_off_t offset, int whence)
+{
+	return errnify(lseek, fildes, offset, whence);
 }