diff --git a/doc/Makefile.in b/doc/Makefile.in
index 3f90ddb..0c2dc26 100644
--- a/doc/Makefile.in
+++ b/doc/Makefile.in
@@ -74,6 +74,7 @@ OBJECTS=CK_ARRAY_FOREACH		\
 	ck_hs_init			\
 	ck_hs_destroy			\
 	CK_HS_HASH			\
+	ck_hs_apply			\
 	ck_hs_iterator_init		\
 	ck_hs_next			\
 	ck_hs_get			\
diff --git a/doc/ck_hs_apply b/doc/ck_hs_apply
new file mode 100644
index 0000000..5664f73
--- /dev/null
+++ b/doc/ck_hs_apply
@@ -0,0 +1,86 @@
+.\"
+.\" Copyright 2014 Samy Al Bahra.
+.\" Copyright 2014 Backtrace I/O, Inc.
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"
+.Dd September 1, 2014
+.Dt CK_HS_APPLY 3
+.Sh NAME
+.Nm ck_hs_apply
+.Nd apply a function to hash set value
+.Sh LIBRARY
+Concurrency Kit (libck, \-lck)
+.Sh SYNOPSIS
+.In ck_hs.h
+.Ft void *
+.Fn ck_hs_apply_fn_t "void *key" "void *closure"
+.Ft bool
+.Fn ck_hs_apply "ck_hs_t *hs" "unsigned long hash" "const void *key" "ck_hs_apply_fn_t *function" "void *argument"
+.Sh DESCRIPTION
+The
+.Fn ck_hs_apply 3
+function will lookup the hash set slot associated with
+.Fa key
+and pass it to function pointed to by
+.Fa function
+for further action. This callback may remove or replace
+the value by respectively returning NULL or a pointer to
+another object with an identical key. The first argument
+passed to
+.Fa function
+is a pointer to the object found in the hash set and
+the second argument is the
+.Fa argument
+pointer passed to
+.Fn ck_hs_apply 3 .
+If the pointer returned by
+.Fa function
+is equivalent to the first argument then no modification
+is made to the hash set.
+.Sh RETURN VALUES
+Upon successful completion,
+.Fn ck_hs_apply 3
+returns true and otherwise returns false on failure.
+.Sh SEE ALSO
+.Xr ck_hs_init 3 ,
+.Xr ck_hs_move 3 ,
+.Xr ck_hs_destroy 3 ,
+.Xr ck_hs_fas 3 ,
+.Xr CK_HS_HASH 3 ,
+.Xr ck_hs_iterator_init 3 ,
+.Xr ck_hs_next 3 ,
+.Xr ck_hs_get 3 ,
+.Xr ck_hs_put 3 ,
+.Xr ck_hs_put_unique 3 ,
+.Xr ck_hs_remove 3 ,
+.Xr ck_hs_grow 3 ,
+.Xr ck_hs_rebuild 3 ,
+.Xr ck_hs_gc 3 ,
+.Xr ck_hs_count 3 ,
+.Xr ck_hs_reset 3 ,
+.Xr ck_hs_reset_size 3 ,
+.Xr ck_hs_stat 3
+.Pp
+Additional information available at http://concurrencykit.org/