diff --git a/Makefile b/Makefile
index 11786ac..3136130 100644
--- a/Makefile
+++ b/Makefile
@@ -3,6 +3,7 @@
 all: thin_repair thin_dump thin_restore
 
 SOURCE=\
+	checksum.cc \
 	endian_utils.cc \
 	error_set.cc \
 	metadata.cc \
@@ -14,7 +15,7 @@ OBJECTS=$(subst .cc,.o,$(SOURCE))
 TOP_DIR:=$(PWD)
 CPPFLAGS=-Wall -g -I$(TOP_DIR)
 #CPPFLAGS=-Wall -std=c++0x -g -I$(TOP_DIR)
-LIBS=-lstdc++
+LIBS=-lz -lstdc++
 
 .PHONEY: test-programs
 
diff --git a/checksum.cc b/checksum.cc
new file mode 100644
index 0000000..4dd37ab
--- /dev/null
+++ b/checksum.cc
@@ -0,0 +1,25 @@
+#include "checksum.h"
+
+#include <zlib.h>
+
+using namespace base;
+
+//----------------------------------------------------------------
+
+crc32::crc32(uint32_t seed)
+	: sum_(seed) {
+}
+
+void
+crc32::append(void const *buffer, unsigned len)
+{
+	sum_ = ::crc32(sum_, reinterpret_cast<Bytef const *>(buffer), len);
+}
+
+uint32_t
+crc32::get_sum() const
+{
+	return sum_;
+}
+
+//----------------------------------------------------------------
diff --git a/checksum.h b/checksum.h
new file mode 100644
index 0000000..76f4f9d
--- /dev/null
+++ b/checksum.h
@@ -0,0 +1,22 @@
+#ifndef CHECKSUM_H
+#define CHECKSUM_H
+
+#include <stdint.h>
+
+//----------------------------------------------------------------
+
+namespace base {
+	class crc32 {
+		crc32(uint32_t seed);
+
+		void append(void const *buffer, unsigned len);
+		uint32_t get_sum() const;
+
+	private:
+		uint32_t sum_;
+	};
+}
+
+//----------------------------------------------------------------
+
+#endif