diff --git a/docs/src/values.html b/docs/src/values.html
index eab1931..933438e 100644
--- a/docs/src/values.html
+++ b/docs/src/values.html
@@ -202,7 +202,7 @@ <h2 id="date-formatting">Formatting</h2>
   <li><code>%%</code>: A literal percent character.</li>
 </ul>
 <p>
-  If no specification is given, Date values default to <code>%Y-%m-%d %H:%M:%S</code>.
+  If no specification is given, Date values default to the original input text or <code>%Y-%m-%d %H:%M:%S</code> if none exists.
 </p>
 
 <div class="demo">
@@ -291,7 +291,7 @@ <h3>Examples</h3>
 <h2 id="datedelta-formatting">Formatting</h2>
 <p>
   DateDelta does not provide formatting options at the moment.
-  By default values are formatted as <code>+Dd HH:MM:SS</code>.
+  By default values are returned as they were input or are formatted as <code>+Dd HH:MM:SS</code> if no original input exists.
   Use attributes to assemble a custom format.
 </p>
 </article>
diff --git a/test/test_values.js b/test/test_values.js
index 6ee0a87..ce64853 100644
--- a/test/test_values.js
+++ b/test/test_values.js
@@ -120,11 +120,17 @@ describe("Value formatting", function () {
     });
 
     it("DateDeltaValue default format", function() {
-        let pos  = new DateDeltaValue("+5m");
+        const pos  = new DateDeltaValue("+5m");
+        assert.strictEqual(pos.toString(), "+5m");
+        pos._TEXT = null; // TODO create a proper mechanism to obtain default formatting
         assert.strictEqual(pos.toString(), "+0d 00:05:00");
-        let neg  = new DateDeltaValue("-251h");
+        const neg  = new DateDeltaValue("-251h");
+        assert.strictEqual(neg.toString(), "-251h");
+        neg._TEXT = null; // TODO create a proper mechanism to obtain default formatting
         assert.strictEqual(neg.toString(), "-10d 11:00:00");
-        let zero = new DateDeltaValue("0d");
+        const zero = new DateDeltaValue("0d");
+        assert.strictEqual(zero.toString(), "0d");
+        zero._TEXT = null; // TODO create a proper mechanism to obtain default formatting
         assert.strictEqual(zero.toString(), "+0d 00:00:00");
     });