diff -u b/tests/memcache.test b/tests/memcache.test
--- b/tests/memcache.test
+++ b/tests/memcache.test
@@ -406,7 +406,7 @@
                       && $this->checkCacheExists('test_cid_clear_future', $this->default_value),
                       t('Three cache items were created for checking cache expiry.'));
 
-    // This should clear only exirable items (CACHE_TEMPORARY).
+    // This should clear only expirable items (CACHE_TEMPORARY).
     cache_clear_all(NULL, $this->default_bin, TRUE);
 
     $this->assertFalse($this->checkCacheExists('test_cid_clear_temporary', $this->default_value),