diff --git a/src/main/java/com/ethlo/time/DateTime.java b/src/main/java/com/ethlo/time/DateTime.java
index 7ba0118..b177611 100644
--- a/src/main/java/com/ethlo/time/DateTime.java
+++ b/src/main/java/com/ethlo/time/DateTime.java
@@ -256,14 +256,14 @@ private String toString(final DateTime date, final Field lastIncluded, final int
         {
             throw new DateTimeException("Requested granularity was " + lastIncluded.name() + ", but contains only granularity " + date.getField().name());
         }
-        final boolean hasTz = date.getOffset().isPresent();
-        final char[] buffer = new char[32];
+        final TimezoneOffset tz = date.getOffset().orElse(null);
+        final char[] buffer = new char[35];
 
         // YEAR
         LimitedCharArrayIntegerUtil.toString(date.getYear(), buffer, 0, 4);
         if (lastIncluded == Field.YEAR)
         {
-            return finish(buffer, Field.YEAR.getRequiredLength(), false);
+            return finish(buffer, Field.YEAR.getRequiredLength(), null);
         }
 
         // MONTH
@@ -274,7 +274,7 @@ private String toString(final DateTime date, final Field lastIncluded, final int
         }
         if (lastIncluded == Field.MONTH)
         {
-            return finish(buffer, Field.MONTH.getRequiredLength(), false);
+            return finish(buffer, Field.MONTH.getRequiredLength(), null);
         }
 
         // DAY
@@ -285,7 +285,7 @@ private String toString(final DateTime date, final Field lastIncluded, final int
         }
         if (lastIncluded == Field.DAY)
         {
-            return finish(buffer, Field.DAY.getRequiredLength(), false);
+            return finish(buffer, Field.DAY.getRequiredLength(), null);
         }
 
         // HOUR
@@ -296,7 +296,7 @@ private String toString(final DateTime date, final Field lastIncluded, final int
         }
         if (lastIncluded == Field.HOUR)
         {
-            return finish(buffer, Field.HOUR.getRequiredLength(), hasTz);
+            return finish(buffer, Field.HOUR.getRequiredLength(), tz);
         }
 
         // MINUTE
@@ -307,7 +307,7 @@ private String toString(final DateTime date, final Field lastIncluded, final int
         }
         if (lastIncluded == Field.MINUTE)
         {
-            return finish(buffer, Field.MINUTE.getRequiredLength(), hasTz);
+            return finish(buffer, Field.MINUTE.getRequiredLength(), tz);
         }
 
         // SECOND
@@ -318,7 +318,7 @@ private String toString(final DateTime date, final Field lastIncluded, final int
         }
         if (lastIncluded == Field.SECOND)
         {
-            return finish(buffer, Field.SECOND.getRequiredLength(), hasTz);
+            return finish(buffer, Field.SECOND.getRequiredLength(), tz);
         }
 
         // Fractions
@@ -327,7 +327,12 @@ private String toString(final DateTime date, final Field lastIncluded, final int
             buffer[19] = '.';
             LimitedCharArrayIntegerUtil.toString(date.getNano(), buffer, 20, fractionDigits);
         }
-        return finish(buffer, 20 + fractionDigits, hasTz);
+        return finish(buffer, 20 + fractionDigits, tz);
     }
 
+    @Override
+    public String toString()
+    {
+        return toString(field);
+    }
 }
diff --git a/src/main/java/com/ethlo/time/internal/EthloITU.java b/src/main/java/com/ethlo/time/internal/EthloITU.java
index 59c08c1..4e0daa9 100644
--- a/src/main/java/com/ethlo/time/internal/EthloITU.java
+++ b/src/main/java/com/ethlo/time/internal/EthloITU.java
@@ -202,24 +202,25 @@ private String doFormatUtc(OffsetDateTime date, Field lastIncluded, int fraction
         {
             utc = date.atZoneSameInstant(FastUTCZoneId.get()).toOffsetDateTime();
         }
+        final TimezoneOffset tz = TimezoneOffset.UTC;
 
         final char[] buffer = new char[31];
 
         if (handleDatePart(lastIncluded, buffer, utc.getYear(), 0, 4, Field.YEAR))
         {
-            return finish(buffer, Field.YEAR.getRequiredLength(), false);
+            return finish(buffer, Field.YEAR.getRequiredLength(), null);
         }
 
         buffer[4] = DATE_SEPARATOR;
         if (handleDatePart(lastIncluded, buffer, utc.getMonthValue(), 5, 2, Field.MONTH))
         {
-            return finish(buffer, Field.MONTH.getRequiredLength(), false);
+            return finish(buffer, Field.MONTH.getRequiredLength(), null);
         }
 
         buffer[7] = DATE_SEPARATOR;
         if (handleDatePart(lastIncluded, buffer, utc.getDayOfMonth(), 8, 2, Field.DAY))
         {
-            return finish(buffer, Field.DAY.getRequiredLength(), false);
+            return finish(buffer, Field.DAY.getRequiredLength(), null);
         }
 
         // T separator
@@ -230,7 +231,7 @@ private String doFormatUtc(OffsetDateTime date, Field lastIncluded, int fraction
         buffer[13] = TIME_SEPARATOR;
         if (handleDatePart(lastIncluded, buffer, utc.getMinute(), 14, 2, Field.MINUTE))
         {
-            return finish(buffer, Field.MINUTE.getRequiredLength(), true);
+            return finish(buffer, Field.MINUTE.getRequiredLength(), tz);
         }
         buffer[16] = TIME_SEPARATOR;
         LimitedCharArrayIntegerUtil.toString(utc.getSecond(), buffer, 17, 2);
@@ -241,9 +242,9 @@ private String doFormatUtc(OffsetDateTime date, Field lastIncluded, int fraction
         {
             buffer[19] = FRACTION_SEPARATOR;
             addFractions(buffer, fractionDigits, utc.getNano());
-            return finish(buffer, 20 + fractionDigits, true);
+            return finish(buffer, 20 + fractionDigits, tz);
         }
-        return finish(buffer, 19, true);
+        return finish(buffer, 19, tz);
     }
 
     private boolean handleDatePart(final Field lastIncluded, final char[] buffer, final int value, final int offset, final int length, final Field field)
@@ -252,13 +253,31 @@ private boolean handleDatePart(final Field lastIncluded, final char[] buffer, fi
         return lastIncluded == field;
     }
 
-    public static String finish(char[] buf, int length, final boolean tz)
+    public static String finish(char[] buf, int length, final TimezoneOffset tz)
     {
-        if (tz)
+        int tzLen = 0;
+        if (tz != null)
         {
-            buf[length] = ZULU_UPPER;
+            tzLen = writeTz(buf, length, tz);
+        }
+        return new String(buf, 0, length + tzLen);
+    }
+
+    private static int writeTz(char[] buf, int start, TimezoneOffset tz)
+    {
+        if (tz.equals(TimezoneOffset.UTC))
+        {
+            buf[start] = ZULU_UPPER;
+            return 1;
+        }
+        else
+        {
+            buf[start] = tz.getTotalSeconds() < 0 ? MINUS : PLUS;
+            LimitedCharArrayIntegerUtil.toString(tz.getHours(), buf, start + 1, 2);
+            buf[start + 3] = TIME_SEPARATOR;
+            LimitedCharArrayIntegerUtil.toString(tz.getMinutes(), buf, start + 4, 2);
+            return 6;
         }
-        return new String(buf, 0, length + (tz ? 1 : 0));
     }
 
     private void addFractions(char[] buf, int fractionDigits, int nano)
diff --git a/src/test/java/com/ethlo/time/W3cCorrectnessTest.java b/src/test/java/com/ethlo/time/W3cCorrectnessTest.java
index b880805..2f82276 100644
--- a/src/test/java/com/ethlo/time/W3cCorrectnessTest.java
+++ b/src/test/java/com/ethlo/time/W3cCorrectnessTest.java
@@ -95,17 +95,20 @@ public void testParseYearMonth()
     @Test
     public void testParseDate()
     {
-        final DateTime date = w3cDateUtil.parse("2012-03-29");
+        final String input = "2012-03-29";
+        final DateTime date = w3cDateUtil.parse(input);
         assertThat(date.getYear()).isEqualTo(2012);
         assertThat(date.getMonth()).isEqualTo(3);
         assertThat(date.getDayOfMonth()).isEqualTo(29);
         assertThat(date.getField()).isEqualTo(Field.DAY);
+        assertThat(date.toString()).isEqualTo(input);
     }
 
     @Test
     public void testParseDateTimeNanos()
     {
-        final DateTime date = w3cDateUtil.parse("2012-10-27T17:22:39.123456789+13:30");
+        final String input = "2012-10-27T17:22:39.123456789+13:30";
+        final DateTime date = w3cDateUtil.parse(input);
         assertThat(date.getYear()).isEqualTo(2012);
         assertThat(date.getMonth()).isEqualTo(10);
         assertThat(date.getDayOfMonth()).isEqualTo(27);
@@ -118,6 +121,7 @@ public void testParseDateTimeNanos()
         assertThat(date.getOffset().get().getHours()).isEqualTo(13);
         assertThat(date.getOffset().get().getMinutes()).isEqualTo(30);
         assertThat(date.getOffset()).hasValue(TimezoneOffset.ofHoursMinutes(13, 30));
+        assertThat(date.toString(9)).isEqualTo(input);
     }
 
     @Test