diff --git a/cache/classes/loaders.php b/cache/classes/loaders.php
index 9d623e2faf6..e0a7723e079 100644
--- a/cache/classes/loaders.php
+++ b/cache/classes/loaders.php
@@ -1270,7 +1270,9 @@ class cache_application extends cache implements cache_loader_with_locking {
                 $this->delete_many($todelete);
             }
             // Set the time of the last invalidation.
-            $this->set('lastinvalidation', cache::now());
+            if ($purgeall || !empty($todelete)) {
+                $this->set('lastinvalidation', cache::now());
+            }
         }
     }
 
@@ -1669,7 +1671,9 @@ class cache_session extends cache {
                 $this->delete_many($todelete);
             }
             // Set the time of the last invalidation.
-            $this->set('lastsessioninvalidation', cache::now());
+            if ($purgeall || !empty($todelete)) {
+                $this->set('lastsessioninvalidation', cache::now());
+            }
         }
     }
 
diff --git a/cache/tests/cache_test.php b/cache/tests/cache_test.php
index 0d6daa71cd8..6c9f14ccae1 100644
--- a/cache/tests/cache_test.php
+++ b/cache/tests/cache_test.php
@@ -989,6 +989,48 @@ class core_cache_testcase extends advanced_testcase {
         ));
         $cache = cache::make('phpunit', 'eventinvalidationtest');
         $this->assertFalse($cache->get('testkey1'));
+
+        // Test 3: Verify that an existing lastinvalidation cache file is updated when needed.
+
+        // Make a new cache class.  This should should invalidate testkey2.
+        $cache = cache::make('phpunit', 'eventinvalidationtest');
+        // Timestamp should have updated to cache::now().
+        $this->assertEquals(cache::now(), $cache->get('lastinvalidation'));
+
+        // Set testkey2 data.
+        $cache->set('testkey2', 'test data 2');
+        // Backdate the event invalidation time by 30 seconds.
+        $invalidationcache = cache::make('core', 'eventinvalidation');
+        $invalidationcache->set('crazyevent', array('testkey2' => cache::now() - 30));
+        // Lastinvalidation should already be cache::now().
+        $this->assertEquals(cache::now(), $cache->get('lastinvalidation'));
+        // Set it to 15 seconds ago so that we know if it changes.
+        $cache->set('lastinvalidation', cache::now() - 15);
+        // Make a new cache class.  This should not invalidate anything.
+        cache_factory::instance()->reset_cache_instances();
+        $cache = cache::make('phpunit', 'eventinvalidationtest');
+        // Lastinvalidation shouldn't change since it was already newer than invalidation event.
+        $this->assertEquals(cache::now() - 15, $cache->get('lastinvalidation'));
+
+        // Now set the event invalidation to newer than the lastinvalidation time.
+        $invalidationcache->set('crazyevent', array('testkey2' => cache::now() - 5));
+        // Make a new cache class.  This should should invalidate testkey2.
+        cache_factory::instance()->reset_cache_instances();
+        $cache = cache::make('phpunit', 'eventinvalidationtest');
+        // Lastinvalidation timestamp should have updated to cache::now().
+        $this->assertEquals(cache::now(), $cache->get('lastinvalidation'));
+
+        // Now simulate a purge_by_event 5 seconds ago.
+        $invalidationcache = cache::make('core', 'eventinvalidation');
+        $invalidationcache->set('crazyevent', array('purged' => cache::now() - 5));
+        // Set our lastinvalidation timestamp to 15 seconds ago.
+        $cache->set('lastinvalidation', cache::now() - 15);
+        // Make a new cache class.  This should invalidate the cache.
+        cache_factory::instance()->reset_cache_instances();
+        $cache = cache::make('phpunit', 'eventinvalidationtest');
+        // Lastinvalidation timestamp should have updated to cache::now().
+        $this->assertEquals(cache::now(), $cache->get('lastinvalidation'));
+
     }
 
     /**