diff --git a/lib/Apc.php b/lib/Apc.php
index fe7ba56f1..579d9c2fc 100644
--- a/lib/Apc.php
+++ b/lib/Apc.php
@@ -21,7 +21,10 @@ class Apc extends BaseCache
      */
     public function get($key, $expire = null, $fn = null)
     {
-        $result = apc_fetch($this->namespace . $key);
+        $result = apc_fetch($this->namespace . $key, $success);
+        if (!$success) {
+            $result = null;
+        }
         return $this->processGetResult($key, $result, $expire, $fn);
     }
 
diff --git a/lib/ArrayCache.php b/lib/ArrayCache.php
index ee22b794f..27b9ca3d0 100644
--- a/lib/ArrayCache.php
+++ b/lib/ArrayCache.php
@@ -30,7 +30,7 @@ public function get($key, $expire = null, $fn = null)
     {
         $oriKey = $key;
         $key = $this->namespace . $key;
-        $result = array_key_exists($key, $this->data) ? $this->data[$key] : false;
+        $result = array_key_exists($key, $this->data) ? $this->data[$key] : null;
         return $this->processGetResult($oriKey, $result, $expire, $fn);
     }
 
diff --git a/lib/BaseCache.php b/lib/BaseCache.php
index 7364e658e..cf818ca8f 100644
--- a/lib/BaseCache.php
+++ b/lib/BaseCache.php
@@ -233,7 +233,7 @@ abstract public function clear();
      */
     protected function processGetResult($key, $result, $expire, $fn)
     {
-        if (false === $result && ($expire || $fn)) {
+        if (null === $result && ($expire || $fn)) {
             // Avoid using null as expire second, for null will be convert to 0
             // which means that store the cache forever, and make it hart to debug.
             if (!is_numeric($expire) && $fn) {
diff --git a/lib/Bicache.php b/lib/Bicache.php
index 4d4244975..860810b3a 100644
--- a/lib/Bicache.php
+++ b/lib/Bicache.php
@@ -39,7 +39,7 @@ class Bicache extends BaseCache
     public function get($key, $expire = null, $fn = null)
     {
         $result = $this->master->get($key);
-        if (false === $result) {
+        if (null === $result) {
             $result = $this->slave->get($key);
         }
         return $this->processGetResult($key, $result, $expire, $fn);
diff --git a/lib/DbCache.php b/lib/DbCache.php
index ea09e4e76..0fb0d213d 100644
--- a/lib/DbCache.php
+++ b/lib/DbCache.php
@@ -98,7 +98,7 @@ public function get($key, $expire = null, $fn = null)
             $result = $this->db->select($this->table, $this->namespace . $key);
             $result = unserialize($result['value']);
         } else {
-            $result = false;
+            $result = null;
         }
         return $this->processGetResult($key, $result, $expire, $fn);
     }
diff --git a/lib/FileCache.php b/lib/FileCache.php
index dce366f51..726ae474c 100644
--- a/lib/FileCache.php
+++ b/lib/FileCache.php
@@ -67,14 +67,14 @@ public function __construct(array $options = [])
     public function get($key, $expire = null, $fn = null)
     {
         if (!is_file($file = $this->getFile($key))) {
-            $result = false;
+            $result = null;
         } else {
             $content = $this->getContent($file);
             if ($content && is_array($content) && time() < $content[0]) {
                 $result = $content[1];
             } else {
                 $this->remove($key);
-                $result = false;
+                $result = null;
             }
         }
         return $this->processGetResult($key, $result, $expire, $fn);
diff --git a/lib/Memcache.php b/lib/Memcache.php
index c27fc3215..db4d9788c 100644
--- a/lib/Memcache.php
+++ b/lib/Memcache.php
@@ -80,7 +80,11 @@ public function __invoke($key = null, $value = null, $expire = 0)
      */
     public function get($key, $expire = null, $fn = null)
     {
-        $result = $this->object->get($this->namespace . $key);
+        $flags = false;
+        $result = $this->object->get($this->namespace . $key, $flags);
+        if ($flags === false) {
+            $result = null;
+        }
         return $this->processGetResult($key, $result, $expire, $fn);
     }
 
diff --git a/lib/Memcached.php b/lib/Memcached.php
index 3aa9023f3..0d59e646a 100644
--- a/lib/Memcached.php
+++ b/lib/Memcached.php
@@ -92,6 +92,9 @@ public function __invoke($key = null, $value = null, $expire = 0)
     public function get($key, $expire = null, $fn = null)
     {
         $result = $this->object->get($this->namespace . $key);
+        if ($this->object->getResultCode() !== \Memcached::RES_SUCCESS) {
+            $result = null;
+        }
         return $this->processGetResult($key, $result, $expire, $fn);
     }
 
diff --git a/lib/MongoCache.php b/lib/MongoCache.php
index 223e7e90a..e62b4e60e 100644
--- a/lib/MongoCache.php
+++ b/lib/MongoCache.php
@@ -76,7 +76,7 @@ public function get($key, $expire = null, $fn = null)
     {
         $result = $this->object->findOne(['_id' => $this->namespace . $key], ['value', 'expire']);
         if (null === $result || $result['expire'] < time()) {
-            $result = false;
+            $result = null;
         } else {
             $result = unserialize($result['value']);
         }
diff --git a/lib/NearCache.php b/lib/NearCache.php
index f02058b73..fce21a95f 100644
--- a/lib/NearCache.php
+++ b/lib/NearCache.php
@@ -26,9 +26,9 @@ class NearCache extends BaseCache
     public function get($key, $expire = null, $fn = null)
     {
         $result = $this->front->get($key);
-        if (false === $result) {
+        if (null === $result) {
             $result = $this->back->get($key);
-            if (false !== $result) {
+            if (null !== $result) {
                 $this->front->set($key, $result, $expire);
             }
         }
diff --git a/lib/Redis.php b/lib/Redis.php
index 490998e21..122bbe9da 100644
--- a/lib/Redis.php
+++ b/lib/Redis.php
@@ -136,7 +136,11 @@ public function connect()
      */
     public function get($key, $expire = null, $fn = null)
     {
-        $result = $this->unserialize($this->object->get($this->namespace . $key));
+        $result = $this->object->get($this->namespace . $key);
+        if (false === $result) {
+            $result = null;
+        }
+        $result = $this->unserialize($result);
         return $this->processGetResult($key, $result, $expire, $fn);
     }
 
@@ -225,7 +229,7 @@ public function add($key, $value, $expire = 0)
      */
     public function replace($key, $value, $expire = 0)
     {
-        if (false === $this->get($key)) {
+        if (false === $this->object->get($this->namespace . $key)) {
             return false;
         }
         return $this->set($key, $this->serialize($value), $expire);
diff --git a/tests/unit/CacheTestCase.php b/tests/unit/CacheTestCase.php
index f6d903b40..1687586e8 100644
--- a/tests/unit/CacheTestCase.php
+++ b/tests/unit/CacheTestCase.php
@@ -25,7 +25,7 @@ public function testGetterAndSetter($value, $key)
         $cache = $this->object;
 
         $cache->remove($key);
-        $this->assertFalse($cache->get($key));
+        $this->assertNull($cache->get($key));
 
         $this->assertFalse($cache->replace($key, $value));
         $this->assertTrue($cache->add($key, $value));
@@ -92,7 +92,7 @@ public function testClear()
         $this->assertEquals($key, $cache->get($key));
 
         $cache->clear();
-        $this->assertFalse($cache->get($key));
+        $this->assertNull($cache->get($key));
     }
 
     public function testInvoker()
diff --git a/tests/unit/DbCacheTest.php b/tests/unit/DbCacheTest.php
index 8b7820838..d559f24e1 100644
--- a/tests/unit/DbCacheTest.php
+++ b/tests/unit/DbCacheTest.php
@@ -43,6 +43,6 @@ public function testExpire()
         //sleep(2);
 
         $result = $cache->get($key);
-        $this->assertFalse($result);
+        $this->assertNull($result);
     }
 }
diff --git a/tests/unit/FileCacheTest.php b/tests/unit/FileCacheTest.php
index 9ca68f29c..23b9ef6c2 100644
--- a/tests/unit/FileCacheTest.php
+++ b/tests/unit/FileCacheTest.php
@@ -70,11 +70,11 @@ public function testGet()
 
         $wei->remove('test');
 
-        $this->assertFalse($wei->get('test'), 'cache has been removed');
+        $this->assertNull($wei->get('test'), 'cache has been removed');
 
         $wei->set('test', __METHOD__, -1);
 
-        $this->assertFalse($wei->get('test'), 'cache is expired');
+        $this->assertNull($wei->get('test'), 'cache is expired');
     }
 
     public function testSet()
@@ -100,7 +100,7 @@ public function testReplace()
 
         $cache->replace('test', __CLASS__);
 
-        $this->assertFalse($cache->get('test'), 'cache not found');
+        $this->assertNull($cache->get('test'), 'cache not found');
 
         $cache->set(__METHOD__, true, -1);
 
@@ -115,7 +115,7 @@ public function testRemove()
 
         $wei->remove('test');
 
-        $this->assertFalse($wei->get('test'));
+        $this->assertNull($wei->get('test'));
 
         $this->assertFalse($wei->remove('test'), 'cache not found');
     }
diff --git a/tests/unit/RedisTest.php b/tests/unit/RedisTest.php
index 0a60b8141..ca9436ac7 100644
--- a/tests/unit/RedisTest.php
+++ b/tests/unit/RedisTest.php
@@ -55,6 +55,6 @@ public function testAddWithExpire()
         // sleep for 1.1s
         usleep(1100000);
 
-        $this->assertFalse($cache->get(__METHOD__));
+        $this->assertNull($cache->get(__METHOD__));
     }
 }
diff --git a/tests/unit/TagCacheTest.php b/tests/unit/TagCacheTest.php
index 9a129eaef..a59801c45 100644
--- a/tests/unit/TagCacheTest.php
+++ b/tests/unit/TagCacheTest.php
@@ -41,7 +41,7 @@ public function testTwoTags()
 
         $this->assertEquals('The content of first post', $cache->get('1'));
 
-        $this->assertFalse($postCache->get('1'));
+        $this->assertNull($postCache->get('1'));
 
         $puCache->clear();
         $postCache->clear();
@@ -56,7 +56,7 @@ public function testClear()
         $postCache->set('1', 'This is the first post');
         $postCache->clear();
 
-        $this->assertFalse($postCache->get('1'));
+        $this->assertNull($postCache->get('1'));
 
         // Clear tag caches have no effect with other caches
         $this->assertEquals('The content of first post', $cache->get('1'));
@@ -80,10 +80,10 @@ public function testClearTag()
 
         $userCache->clear();
 
-        $this->assertFalse($userCache->get('1'));
+        $this->assertNull($userCache->get('1'));
         $this->assertEquals('This is the first post, from admin', $puCache->get('1-1'));
 
-        $this->assertFalse($puCache->reload()->get('1-1'));
+        $this->assertNull($puCache->reload()->get('1-1'));
         $this->assertEquals('This is the first post', $postCache->get('1'));
 
         $puCache->clear();