diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index a865cf3..4de4594 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -319,6 +319,21 @@ rb_zlib_adler32(int argc, VALUE *argv, VALUE klass)
 }
 
 /*
+ * call-seq: Zlib.adler32_combine(adler1, adler2, len2)
+ *
+ * Combine two Adler-32 check values in to one.  +alder1+ is the first Adler-32
+ * value, +adler2+ is the second Adler-32 value.  +len2+ is the length of the
+ * string used to generate +adler2+.
+ *
+ */
+static VALUE
+rb_zlib_adler32_combine(VALUE klass, VALUE adler1, VALUE adler2, VALUE len2)
+{
+  return ULONG2NUM(
+	adler32_combine(NUM2ULONG(adler1), NUM2ULONG(adler2), NUM2LONG(len2)));
+}
+
+/*
  * call-seq: Zlib.crc32(string, adler)
  *
  * Calculates CRC checksum for +string+, and returns updated value of +crc+. If
@@ -334,6 +349,21 @@ rb_zlib_crc32(int argc, VALUE *argv, VALUE klass)
 }
 
 /*
+ * call-seq: Zlib.crc32_combine(crc1, crc2, len2)
+ *
+ * Combine two CRC-32 check values in to one.  +crc1+ is the first CRC-32
+ * value, +crc2+ is the second CRC-32 value.  +len2+ is the length of the
+ * string used to generate +crc2+.
+ *
+ */
+static VALUE
+rb_zlib_crc32_combine(VALUE klass, VALUE crc1, VALUE crc2, VALUE len2)
+{
+  return ULONG2NUM(
+	crc32_combine(NUM2ULONG(crc1), NUM2ULONG(crc2), NUM2LONG(len2)));
+}
+
+/*
  * Returns the table for calculating CRC checksum as an array.
  */
 static VALUE
@@ -3468,7 +3498,9 @@ Init_zlib()
 
     rb_define_module_function(mZlib, "zlib_version", rb_zlib_version, 0);
     rb_define_module_function(mZlib, "adler32", rb_zlib_adler32, -1);
+    rb_define_module_function(mZlib, "adler32_combine", rb_zlib_adler32_combine, 3);
     rb_define_module_function(mZlib, "crc32", rb_zlib_crc32, -1);
+    rb_define_module_function(mZlib, "crc32_combine", rb_zlib_crc32_combine, 3);
     rb_define_module_function(mZlib, "crc_table", rb_zlib_crc_table, 0);
 
     rb_define_const(mZlib, "VERSION", rb_str_new2(RUBY_ZLIB_VERSION));
diff --git a/test/zlib/test_zlib.rb b/test/zlib/test_zlib.rb
index abb3ea3..6982db7 100644
--- a/test/zlib/test_zlib.rb
+++ b/test/zlib/test_zlib.rb
@@ -662,6 +662,12 @@ if defined? Zlib
       assert_equal(0x8a62c964, Zlib.adler32("abc\x01\x02\x03" * 10000))
     end
 
+    def test_adler32_combine
+      one = Zlib.adler32("fo")
+      two = Zlib.adler32("o")
+      assert_equal(0x02820145, Zlib.adler32_combine(one, two, 1))
+    end
+
     def test_crc32
       assert_equal(0x00000000, Zlib.crc32)
       assert_equal(0x8c736521, Zlib.crc32("foo"))
@@ -669,6 +675,12 @@ if defined? Zlib
       assert_equal(0x07f0d68f, Zlib.crc32("abc\x01\x02\x03" * 10000))
     end
 
+    def test_crc32_combine
+      one = Zlib.crc32("fo")
+      two = Zlib.crc32("o")
+      assert_equal(0x8c736521, Zlib.crc32_combine(one, two, 1))
+    end
+
     def test_crc_table
       t = Zlib.crc_table
       assert_instance_of(Array, t)