diff --git a/src/DateTimeMock/DateTimeMock.php b/src/DateTimeMock/DateTimeMock.php
index 54dcd9f..fab5135 100644
--- a/src/DateTimeMock/DateTimeMock.php
+++ b/src/DateTimeMock/DateTimeMock.php
@@ -28,12 +28,15 @@ public function __construct(?string $datetime = 'now', ?DateTimeZone $timezone =
         if ($timezone !== null && !$isDateTimeStringRelative) {
             // When there's a timezone and the provided date is absolute, the timestamp must be calculated with that
             // specific timezone in order to mimic behavior of the original \DateTime (which does not modify time).
-            $this->setTimestamp(
-                strtotime(
-                    "$datetime {$timezone->getName()}",
-                    ClockMock::getFrozenDateTime()->getTimestamp()
-                )
-            );
+            $timestamp = strtotime("$datetime {$timezone->getName()}", ClockMock::getFrozenDateTime()->getTimestamp());
+            if ($timestamp === false) {
+                // Some non-canonical timezone names (e.g. US/Eastern) are not supported by `strtotime`. In these cases,
+                // apply the same workaround by using the offset in seconds.
+                $offset = -$timezone->getOffset(new \DateTime('now'));
+                $timestamp = strtotime("$datetime $offset seconds", ClockMock::getFrozenDateTime()->getTimestamp());
+            }
+
+            $this->setTimestamp($timestamp);
         } else {
             $this->setTimestamp(strtotime($datetime, ClockMock::getFrozenDateTime()->getTimestamp()));
         }
diff --git a/tests/ClockMockTest.php b/tests/ClockMockTest.php
index c835a4a..e06faba 100644
--- a/tests/ClockMockTest.php
+++ b/tests/ClockMockTest.php
@@ -104,7 +104,7 @@ public function test_DateTime_constructor_with_absolute_mocked_date()
     /**
      * @see https://github.com/slope-it/clock-mock/issues/26
      */
-    public function test_DateTime_constructor_with_absolute_date_and_timezone()
+    public function test_DateTime_constructor_with_absolute_date_and_canonical_timezone()
     {
         // The mocked date, either aboslute or relative, is irrelevant for this test. Having a mocked date is enough.
         ClockMock::freeze(new \DateTime('now'));
@@ -119,6 +119,25 @@ public function test_DateTime_constructor_with_absolute_date_and_timezone()
         $this->assertSame('1986-06-05 12:13:14', $absoluteDateTimeWithTimezone->format('Y-m-d H:i:s'));
     }
 
+    /**
+     * @see https://github.com/slope-it/clock-mock/issues/37
+     * @see https://en.wikipedia.org/wiki/List_of_tz_database_time_zones
+     */
+    public function test_DateTime_constructor_with_absolute_date_and_non_canonical_timezone()
+    {
+        // The mocked date, either aboslute or relative, is irrelevant for this test. Having a mocked date is enough.
+        ClockMock::freeze(new \DateTime('now'));
+
+        $absoluteDateTimeWithTimezone = new \DateTime(
+            '1986-06-05 12:13:14',
+            $usEasternTimezone = new \DateTimeZone('US/Eastern')
+        );
+
+        // Verification: when date is absolute and timezone is specified, the mocked clock should have no effect.
+        $this->assertEquals($usEasternTimezone, $absoluteDateTimeWithTimezone->getTimezone());
+        $this->assertSame('1986-06-05 12:13:14', $absoluteDateTimeWithTimezone->format('Y-m-d H:i:s'));
+    }
+
     /**
      * @see https://github.com/slope-it/clock-mock/issues/31
      */