diff --git a/core/modules/datetime/src/Plugin/views/sort/Date.php b/core/modules/datetime/src/Plugin/views/sort/Date.php
index b86d424..12eddc6 100644
--- a/core/modules/datetime/src/Plugin/views/sort/Date.php
+++ b/core/modules/datetime/src/Plugin/views/sort/Date.php
@@ -43,4 +43,14 @@ public function query() {
     parent::query();
   }
 
+  /**
+   * {@inheritdoc}
+   *
+   * Overridden in order to pass in the string date flag.
+   */
+  public function getDateFormat($format) {
+    return $this->query->getDateFormat($this->getDateField(), $format, TRUE);
+  }
+
+
 }
diff --git a/core/modules/views/src/Plugin/views/query/Sql.php b/core/modules/views/src/Plugin/views/query/Sql.php
index f03b494..61d5ce8 100644
--- a/core/modules/views/src/Plugin/views/query/Sql.php
+++ b/core/modules/views/src/Plugin/views/query/Sql.php
@@ -1833,15 +1833,19 @@ public function getDateFormat($field, $format, $string_date = FALSE) {
           'A' => '',
         );
         $format = strtr($format, $replace);
+
+        // Don't use the 'unixepoch' flag for string date comparisons.
+        $unixepoch = $string_date ? '' : ", 'unixepoch'";
+
         // SQLite does not have a ISO week substitution string, so it needs
         // special handling.
         // @see http://en.wikipedia.org/wiki/ISO_week_date#Calculation
         // @see http://stackoverflow.com/a/15511864/1499564
         if ($format === '%W') {
-          $expression = "((strftime('%j', date(strftime('%Y-%m-%d', $field, 'unixepoch'), '-3 days', 'weekday 4')) - 1) / 7 + 1)";
+          $expression = "((strftime('%j', date(strftime('%Y-%m-%d', $field" . $unixepoch . "), '-3 days', 'weekday 4')) - 1) / 7 + 1)";
         }
         else {
-          $expression = "strftime('$format', $field, 'unixepoch')";
+          $expression = "strftime('$format', $field" . $unixepoch . ")";
         }
         // The expression yields a string, but the comparison value is an
         // integer in case the comparison value is a float, integer, or numeric.