diff --git a/stix2/patterns.py b/stix2/patterns.py
index 7858146..03b7657 100644
--- a/stix2/patterns.py
+++ b/stix2/patterns.py
@@ -24,7 +24,7 @@ class TimestampConstant(_Constant):
         self.value = value
 
     def __str__(self):
-        return "'%s'" % escape_quotes_and_backslashes(self.value)
+        return "t'%s'" % escape_quotes_and_backslashes(self.value)
 
 
 class IntegerConstant(_Constant):
diff --git a/stix2/test/test_pattern_expressions.py b/stix2/test/test_pattern_expressions.py
index e806aa6..0db1083 100644
--- a/stix2/test/test_pattern_expressions.py
+++ b/stix2/test/test_pattern_expressions.py
@@ -170,3 +170,8 @@ def test_set_op():
     exp = stix2.ObservationExpression(stix2.IsSubsetComparisonExpression("network-traffic:dst_ref.value",
                                                                          "2001:0db8:dead:beef:0000:0000:0000:0000/64"))
     assert str(exp) == "[network-traffic:dst_ref.value ISSUBSET '2001:0db8:dead:beef:0000:0000:0000:0000/64']"
+
+
+def test_timestamp():
+    ts = stix2.TimestampConstant('2014-01-13T07:03:17Z')
+    assert str(ts) == "t'2014-01-13T07:03:17Z'"