diff --git a/.gitignore b/.gitignore
index 5c4ca06..de66884 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,5 +15,6 @@ missing
 stamp-h1
 config.h
 *.o
+*.a
 *~
 pkg
diff --git a/Makefile.am b/Makefile.am
index e820c3b..4cd8b39 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3,20 +3,24 @@ ACLOCAL_AMFLAGS = -I m4
 AM_CPPFLAGS = -I$(top_srcdir)/include -D_GNU_SOURCE
 AM_CFLAGS = $(WARN_CFLAGS)
 
-# application core
-GLOBALHDR = include/pkgformat.h include/util.h include/pkgreader.h
-GLOBALHDR += include/compressor.h include/command.h include/pkgwriter.h
-GLOBALHDR += include/image_entry.h include/pkgio.h include/input_file.h
+# helper libraries
+libutil_a_SOURCES = lib/util/input_file.c lib/util/mkdir_p.c lib/util/util.c
+libutil_a_SOURCES += include/util/util.h include/util/input_file.h
 
-MAIN = main/pkg.c main/util.c main/compressor.c main/command.c main/pkgreader.c
+# application core
+GLOBALHDR = include/pkgformat.h include/pkgreader.h
+GLOBALHDR += include/compressor.h include/command.h include/pkgwriter.h
+GLOBALHDR += include/image_entry.h include/pkgio.h
+
+MAIN = main/pkg.c main/compressor.c main/command.c main/pkgreader.c
 MAIN += main/pkgwriter.c main/image_entry.c main/image_entry_sort.c
-MAIN += main/mkdir_p.c main/pkgio_rd_image_entry.c main/pkg_unpack.c
-MAIN += main/input_file.c main/dump_toc.c
+MAIN += main/pkgio_rd_image_entry.c main/pkg_unpack.c main/dump_toc.c
 
 pkg_SOURCES = $(GLOBALHDR) $(MAIN)
 pkg_CFLAGS = $(AM_CFLAGS)
-pkg_LDADD =
+pkg_LDADD = libutil.a
 
+noinst_LIBRARIES = libutil.a
 bin_PROGRAMS = pkg
 
 EXTRA_DIST = autogen.sh
diff --git a/configure.ac b/configure.ac
index 8ebfe14..b9be4ef 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5,6 +5,7 @@ AM_INIT_AUTOMAKE([foreign dist-xz subdir-objects])
 AM_SILENT_RULES([yes])
 AC_PROG_CC
 AC_PROG_CC_C99
+AC_PROG_RANLIB
 AC_PROG_INSTALL
 
 m4_ifndef([PKG_PROG_PKG_CONFIG],
diff --git a/include/input_file.h b/include/util/input_file.h
similarity index 100%
rename from include/input_file.h
rename to include/util/input_file.h
diff --git a/include/util.h b/include/util/util.h
similarity index 100%
rename from include/util.h
rename to include/util/util.h
diff --git a/main/input_file.c b/lib/util/input_file.c
similarity index 98%
rename from main/input_file.c
rename to lib/util/input_file.c
index 30cc306..9ecfa6f 100644
--- a/main/input_file.c
+++ b/lib/util/input_file.c
@@ -3,7 +3,7 @@
 #include <errno.h>
 #include <ctype.h>
 
-#include "input_file.h"
+#include "util/input_file.h"
 
 static int prefetch_line(input_file_t *f)
 {
diff --git a/main/mkdir_p.c b/lib/util/mkdir_p.c
similarity index 96%
rename from main/mkdir_p.c
rename to lib/util/mkdir_p.c
index 11b9de5..950ea4b 100644
--- a/main/mkdir_p.c
+++ b/lib/util/mkdir_p.c
@@ -5,7 +5,7 @@
 #include <stdio.h>
 #include <errno.h>
 
-#include "util.h"
+#include "util/util.h"
 
 int mkdir_p(const char *path)
 {
diff --git a/main/util.c b/lib/util/util.c
similarity index 98%
rename from main/util.c
rename to lib/util/util.c
index 42ecd20..1df9273 100644
--- a/main/util.c
+++ b/lib/util/util.c
@@ -2,7 +2,7 @@
 #include <string.h>
 #include <errno.h>
 
-#include "util.h"
+#include "util/util.h"
 
 int canonicalize_name(char *filename)
 {
diff --git a/main/cmd/dump/dump.h b/main/cmd/dump/dump.h
index 0db98c6..9c69d2c 100644
--- a/main/cmd/dump/dump.h
+++ b/main/cmd/dump/dump.h
@@ -7,12 +7,13 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+#include "util/util.h"
+
 #include "image_entry.h"
 #include "pkgformat.h"
 #include "pkgreader.h"
 #include "command.h"
 #include "pkgio.h"
-#include "util.h"
 
 typedef enum {
 	DUMP_TOC = 0x01,
diff --git a/main/cmd/install/install.h b/main/cmd/install/install.h
index c64f413..a0c852c 100644
--- a/main/cmd/install/install.h
+++ b/main/cmd/install/install.h
@@ -9,11 +9,12 @@
 #include <stdio.h>
 #include <fcntl.h>
 
+#include "util/util.h"
+
 #include "image_entry.h"
 #include "pkgreader.h"
 #include "command.h"
 #include "pkgio.h"
-#include "util.h"
 
 enum {
 	INSTALL_MODE_INSTALL = 0,
diff --git a/main/cmd/pack/pack.h b/main/cmd/pack/pack.h
index 8da895a..40da3d2 100644
--- a/main/cmd/pack/pack.h
+++ b/main/cmd/pack/pack.h
@@ -14,13 +14,14 @@
 #include <ctype.h>
 #include <fcntl.h>
 
+#include "util/input_file.h"
+#include "util/util.h"
+
 #include "image_entry.h"
-#include "input_file.h"
 #include "compressor.h"
 #include "pkgformat.h"
 #include "pkgwriter.h"
 #include "command.h"
-#include "util.h"
 
 typedef struct dependency_t {
 	struct dependency_t *next;
diff --git a/main/cmd/unpack.c b/main/cmd/unpack.c
index 31339b0..1e0e97d 100644
--- a/main/cmd/unpack.c
+++ b/main/cmd/unpack.c
@@ -4,10 +4,11 @@
 #include <stdio.h>
 #include <fcntl.h>
 
+#include "util/util.h"
+
 #include "pkgreader.h"
 #include "command.h"
 #include "pkgio.h"
-#include "util.h"
 
 static const struct option long_opts[] = {
 	{ "root", required_argument, NULL, 'r' },
diff --git a/main/image_entry.c b/main/image_entry.c
index 287a6d5..007cf9d 100644
--- a/main/image_entry.c
+++ b/main/image_entry.c
@@ -3,7 +3,6 @@
 #include <stdio.h>
 
 #include "image_entry.h"
-#include "util.h"
 
 void image_entry_free(image_entry_t *ent)
 {
diff --git a/main/pkg_unpack.c b/main/pkg_unpack.c
index 0864f2a..86db2ab 100644
--- a/main/pkg_unpack.c
+++ b/main/pkg_unpack.c
@@ -7,7 +7,7 @@
 #include <fcntl.h>
 
 #include "pkgio.h"
-#include "util.h"
+#include "util/util.h"
 
 static int create_hierarchy(int dirfd, image_entry_t *list)
 {
diff --git a/main/pkgio_rd_image_entry.c b/main/pkgio_rd_image_entry.c
index c83a850..6c94b12 100644
--- a/main/pkgio_rd_image_entry.c
+++ b/main/pkgio_rd_image_entry.c
@@ -4,7 +4,7 @@
 #include <stdio.h>
 
 #include "pkgio.h"
-#include "util.h"
+#include "util/util.h"
 
 static int read_extra(pkg_reader_t *pkg, image_entry_t *ent)
 {
diff --git a/main/pkgreader.c b/main/pkgreader.c
index db50413..fa4d2c8 100644
--- a/main/pkgreader.c
+++ b/main/pkgreader.c
@@ -7,7 +7,7 @@
 #include <errno.h>
 #include <ctype.h>
 
-#include "util.h"
+#include "util/util.h"
 #include "pkgreader.h"
 #include "compressor.h"
 
diff --git a/main/pkgwriter.c b/main/pkgwriter.c
index 4ca9c8f..4831b46 100644
--- a/main/pkgwriter.c
+++ b/main/pkgwriter.c
@@ -6,7 +6,7 @@
 #include <errno.h>
 
 #include "pkgwriter.h"
-#include "util.h"
+#include "util/util.h"
 
 struct pkg_writer_t {
 	const char *path;