diff --git a/codec/src/main/java/io/netty/handler/codec/DateFormatter.java b/codec/src/main/java/io/netty/handler/codec/DateFormatter.java
index b07912abaa..8c3d2274bd 100644
--- a/codec/src/main/java/io/netty/handler/codec/DateFormatter.java
+++ b/codec/src/main/java/io/netty/handler/codec/DateFormatter.java
@@ -38,10 +38,12 @@ import java.util.TimeZone;
  * If you're looking for a date format that validates day of week, or supports other timezones, consider using
  * java.util.DateTimeFormatter.RFC_1123_DATE_TIME.
  *
- * On the formatting side, it uses RFC1123 format.
+ * On the formatting side, it uses a subset of RFC1123 (2 digit day-of-month and 4 digit year) as per RFC2616.
+ * This subset supports RFC6265.
  *
  * @see <a href="https://tools.ietf.org/html/rfc6265#section-5.1.1">RFC6265</a> for the parsing side
- * @see <a href="https://tools.ietf.org/html/rfc1123#page-55">RFC1123</a> for the encoding side.
+ * @see <a href="https://tools.ietf.org/html/rfc1123#page-55">RFC1123</a> and
+ * <a href="https://tools.ietf.org/html/rfc2616#section-3.3.1">RFC2616</a> for the encoding side.
  */
 public final class DateFormatter {
 
@@ -429,7 +431,7 @@ public final class DateFormatter {
         cal.setTime(date);
 
         sb.append(DAY_OF_WEEK_TO_SHORT_NAME[cal.get(Calendar.DAY_OF_WEEK) - 1]).append(", ");
-        sb.append(cal.get(Calendar.DAY_OF_MONTH)).append(' ');
+        appendZeroLeftPadded(cal.get(Calendar.DAY_OF_MONTH), sb).append(' ');
         sb.append(CALENDAR_MONTH_TO_SHORT_NAME[cal.get(Calendar.MONTH)]).append(' ');
         sb.append(cal.get(Calendar.YEAR)).append(' ');
         appendZeroLeftPadded(cal.get(Calendar.HOUR_OF_DAY), sb).append(':');
diff --git a/codec/src/test/java/io/netty/handler/codec/DateFormatterTest.java b/codec/src/test/java/io/netty/handler/codec/DateFormatterTest.java
index e833fdfb60..6c1f5d09c6 100644
--- a/codec/src/test/java/io/netty/handler/codec/DateFormatterTest.java
+++ b/codec/src/test/java/io/netty/handler/codec/DateFormatterTest.java
@@ -43,90 +43,97 @@ public class DateFormatterTest {
 
     @Test
     public void testParseWithDashSeparatorSingleDigitDay() {
-        assertEquals(DATE, parseHttpDate("Sunday, 06-Nov-94 08:49:37 GMT"));
-    }
-
-    @Test
-    public void testParseWithSingleDoubleDigitDay() {
         assertEquals(DATE, parseHttpDate("Sunday, 6-Nov-94 08:49:37 GMT"));
     }
 
+    @Test
+    public void testParseWithDashSeparatorDoubleDigitDay() {
+        assertEquals(DATE, parseHttpDate("Sunday, 06-Nov-94 08:49:37 GMT"));
+    }
+
     @Test
     public void testParseWithoutGMT() {
-        assertEquals(DATE, parseHttpDate("Sun Nov 6 08:49:37 1994"));
+        assertEquals(DATE, parseHttpDate("Sun Nov 06 08:49:37 1994"));
     }
 
     @Test
     public void testParseWithFunkyTimezone() {
-        assertEquals(DATE, parseHttpDate("Sun Nov 6 08:49:37 1994 -0000"));
+        assertEquals(DATE, parseHttpDate("Sun Nov 06 08:49:37 1994 -0000"));
     }
 
     @Test
     public void testParseWithSingleDigitHourMinutesAndSecond() {
-        assertEquals(DATE, parseHttpDate("Sunday, 6-Nov-94 8:49:37 GMT"));
+        assertEquals(DATE, parseHttpDate("Sunday, 06-Nov-94 8:49:37 GMT"));
     }
 
     @Test
     public void testParseWithSingleDigitTime() {
-        assertEquals(DATE, parseHttpDate("Sunday, 6 Nov 1994 8:49:37 GMT"));
+        assertEquals(DATE, parseHttpDate("Sunday, 06 Nov 1994 8:49:37 GMT"));
 
         Date _08_09_37 = new Date(TIMESTAMP - 40 * 60 * 1000);
-        assertEquals(_08_09_37, parseHttpDate("Sunday, 6 Nov 1994 8:9:37 GMT"));
-        assertEquals(_08_09_37, parseHttpDate("Sunday, 6 Nov 1994 8:09:37 GMT"));
+        assertEquals(_08_09_37, parseHttpDate("Sunday, 06 Nov 1994 8:9:37 GMT"));
+        assertEquals(_08_09_37, parseHttpDate("Sunday, 06 Nov 1994 8:09:37 GMT"));
 
         Date _08_09_07 = new Date(TIMESTAMP - (40 * 60 + 30) * 1000);
-        assertEquals(_08_09_07, parseHttpDate("Sunday, 6 Nov 1994 8:9:7 GMT"));
-        assertEquals(_08_09_07, parseHttpDate("Sunday, 6 Nov 1994 8:9:07 GMT"));
+        assertEquals(_08_09_07, parseHttpDate("Sunday, 06 Nov 1994 8:9:7 GMT"));
+        assertEquals(_08_09_07, parseHttpDate("Sunday, 06 Nov 1994 8:9:07 GMT"));
     }
 
     @Test
     public void testParseMidnight() {
-        assertEquals(new Date(784080000000L), parseHttpDate("Sunday, 6 Nov 1994 00:00:00 GMT"));
+        assertEquals(new Date(784080000000L), parseHttpDate("Sunday, 06 Nov 1994 00:00:00 GMT"));
     }
 
     @Test
     public void testParseInvalidInput() {
         // missing field
         assertNull(parseHttpDate("Sun, Nov 1994 08:49:37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 1994 08:49:37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 08:49:37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 1994 :49:37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 1994 49:37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 1994 08::37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 1994 08:37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 1994 08:49: GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 1994 08:49 GMT"));
+        assertNull(parseHttpDate("Sun, 06 1994 08:49:37 GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 08:49:37 GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 1994 :49:37 GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 1994 49:37 GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 1994 08::37 GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 1994 08:37 GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 1994 08:49: GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 1994 08:49 GMT"));
         //invalid value
-        assertNull(parseHttpDate("Sun, 6 FOO 1994 08:49:37 GMT"));
+        assertNull(parseHttpDate("Sun, 06 FOO 1994 08:49:37 GMT"));
         assertNull(parseHttpDate("Sun, 36 Nov 1994 08:49:37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 1994 28:49:37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 1994 08:69:37 GMT"));
-        assertNull(parseHttpDate("Sun, 6 Nov 1994 08:49:67 GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 1994 28:49:37 GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 1994 08:69:37 GMT"));
+        assertNull(parseHttpDate("Sun, 06 Nov 1994 08:49:67 GMT"));
         //wrong number of digits in timestamp
-        assertNull(parseHttpDate("Sunday, 6 Nov 1994 0:0:000 GMT"));
-        assertNull(parseHttpDate("Sunday, 6 Nov 1994 0:000:0 GMT"));
-        assertNull(parseHttpDate("Sunday, 6 Nov 1994 000:0:0 GMT"));
+        assertNull(parseHttpDate("Sunday, 06 Nov 1994 0:0:000 GMT"));
+        assertNull(parseHttpDate("Sunday, 06 Nov 1994 0:000:0 GMT"));
+        assertNull(parseHttpDate("Sunday, 06 Nov 1994 000:0:0 GMT"));
     }
 
     @Test
     public void testFormat() {
-        assertEquals("Sun, 6 Nov 1994 08:49:37 GMT", format(DATE));
+        assertEquals("Sun, 06 Nov 1994 08:49:37 GMT", format(DATE));
+    }
+
+    @Test
+    public void testAppend() {
+        StringBuilder sb = new StringBuilder();
+        append(DATE, sb);
+        assertEquals("Sun, 06 Nov 1994 08:49:37 GMT", sb.toString());
     }
 
     @Test
     public void testParseAllMonths() {
-        assertEquals(Calendar.JANUARY, getMonth(parseHttpDate("Sun, 6 Jan 1994 08:49:37 GMT")));
-        assertEquals(Calendar.FEBRUARY, getMonth(parseHttpDate("Sun, 6 Feb 1994 08:49:37 GMT")));
-        assertEquals(Calendar.MARCH, getMonth(parseHttpDate("Sun, 6 Mar 1994 08:49:37 GMT")));
-        assertEquals(Calendar.APRIL, getMonth(parseHttpDate("Sun, 6 Apr 1994 08:49:37 GMT")));
-        assertEquals(Calendar.MAY, getMonth(parseHttpDate("Sun, 6 May 1994 08:49:37 GMT")));
-        assertEquals(Calendar.JUNE, getMonth(parseHttpDate("Sun, 6 Jun 1994 08:49:37 GMT")));
-        assertEquals(Calendar.JULY, getMonth(parseHttpDate("Sun, 6 Jul 1994 08:49:37 GMT")));
-        assertEquals(Calendar.AUGUST, getMonth(parseHttpDate("Sun, 6 Aug 1994 08:49:37 GMT")));
-        assertEquals(Calendar.SEPTEMBER, getMonth(parseHttpDate("Sun, 6 Sep 1994 08:49:37 GMT")));
-        assertEquals(Calendar.OCTOBER, getMonth(parseHttpDate("Sun Oct 6 08:49:37 1994")));
-        assertEquals(Calendar.NOVEMBER, getMonth(parseHttpDate("Sun Nov 6 08:49:37 1994")));
-        assertEquals(Calendar.DECEMBER, getMonth(parseHttpDate("Sun Dec 6 08:49:37 1994")));
+        assertEquals(Calendar.JANUARY, getMonth(parseHttpDate("Sun, 06 Jan 1994 08:49:37 GMT")));
+        assertEquals(Calendar.FEBRUARY, getMonth(parseHttpDate("Sun, 06 Feb 1994 08:49:37 GMT")));
+        assertEquals(Calendar.MARCH, getMonth(parseHttpDate("Sun, 06 Mar 1994 08:49:37 GMT")));
+        assertEquals(Calendar.APRIL, getMonth(parseHttpDate("Sun, 06 Apr 1994 08:49:37 GMT")));
+        assertEquals(Calendar.MAY, getMonth(parseHttpDate("Sun, 06 May 1994 08:49:37 GMT")));
+        assertEquals(Calendar.JUNE, getMonth(parseHttpDate("Sun, 06 Jun 1994 08:49:37 GMT")));
+        assertEquals(Calendar.JULY, getMonth(parseHttpDate("Sun, 06 Jul 1994 08:49:37 GMT")));
+        assertEquals(Calendar.AUGUST, getMonth(parseHttpDate("Sun, 06 Aug 1994 08:49:37 GMT")));
+        assertEquals(Calendar.SEPTEMBER, getMonth(parseHttpDate("Sun, 06 Sep 1994 08:49:37 GMT")));
+        assertEquals(Calendar.OCTOBER, getMonth(parseHttpDate("Sun Oct 06 08:49:37 1994")));
+        assertEquals(Calendar.NOVEMBER, getMonth(parseHttpDate("Sun Nov 06 08:49:37 1994")));
+        assertEquals(Calendar.DECEMBER, getMonth(parseHttpDate("Sun Dec 06 08:49:37 1994")));
     }
 
     private static int getMonth(Date referenceDate) {