diff --git a/date_api/lib/Drupal/date_api/DateGranularity.php b/date_api/lib/Drupal/date_api/DateGranularity.php
index 5b6c569..4a7cb93 100644
--- a/date_api/lib/Drupal/date_api/DateGranularity.php
+++ b/date_api/lib/Drupal/date_api/DateGranularity.php
@@ -88,7 +88,7 @@ class DateGranularity {
    *   A single date part.
    */
   public function removeGranularity($part) {
-    if ($key = array_search($part, $this->granularity)) {
+    if (($key = array_search($part, $this->granularity)) !== FALSE) {
       unset($this->granularity[$key]);
     }
   }
@@ -483,4 +483,4 @@ class DateGranularity {
         return self::limitFormat($format, array($part));
     }
   }
-}
\ No newline at end of file
+}