diff --git a/src/Symfony/Component/ClassLoader/ApcClassLoader.php b/src/Symfony/Component/ClassLoader/ApcClassLoader.php
index 4f71ea173d..c21c64e38b 100644
--- a/src/Symfony/Component/ClassLoader/ApcClassLoader.php
+++ b/src/Symfony/Component/ClassLoader/ApcClassLoader.php
@@ -122,8 +122,10 @@ class ApcClassLoader
      */
     public function findFile($class)
     {
-        if (false === $file = apcu_fetch($this->prefix.$class)) {
-            apcu_store($this->prefix.$class, $file = $this->decorated->findFile($class));
+        $file = apcu_fetch($this->prefix.$class, $success);
+
+        if (!$success) {
+            apcu_store($this->prefix.$class, $file = $this->decorated->findFile($class) ?: null);
         }
 
         return $file;
diff --git a/src/Symfony/Component/ClassLoader/ApcUniversalClassLoader.php b/src/Symfony/Component/ClassLoader/ApcUniversalClassLoader.php
index bedb30f895..bad90267ff 100644
--- a/src/Symfony/Component/ClassLoader/ApcUniversalClassLoader.php
+++ b/src/Symfony/Component/ClassLoader/ApcUniversalClassLoader.php
@@ -87,8 +87,10 @@ class ApcUniversalClassLoader extends UniversalClassLoader
      */
     public function findFile($class)
     {
-        if (false === $file = apcu_fetch($this->prefix.$class)) {
-            apcu_store($this->prefix.$class, $file = parent::findFile($class));
+        $file = apcu_fetch($this->prefix.$class, $success);
+
+        if (!$success) {
+            apcu_store($this->prefix.$class, $file = parent::findFile($class) ?: null);
         }
 
         return $file;
diff --git a/src/Symfony/Component/ClassLoader/DebugClassLoader.php b/src/Symfony/Component/ClassLoader/DebugClassLoader.php
index eec68b2c98..53be5b5c87 100644
--- a/src/Symfony/Component/ClassLoader/DebugClassLoader.php
+++ b/src/Symfony/Component/ClassLoader/DebugClassLoader.php
@@ -74,7 +74,7 @@ class DebugClassLoader
      */
     public function findFile($class)
     {
-        return $this->classFinder->findFile($class);
+        return $this->classFinder->findFile($class) ?: null;
     }
 
     /**
diff --git a/src/Symfony/Component/ClassLoader/WinCacheClassLoader.php b/src/Symfony/Component/ClassLoader/WinCacheClassLoader.php
index 0fc11d019f..8c846e3c26 100644
--- a/src/Symfony/Component/ClassLoader/WinCacheClassLoader.php
+++ b/src/Symfony/Component/ClassLoader/WinCacheClassLoader.php
@@ -123,8 +123,10 @@ class WinCacheClassLoader
      */
     public function findFile($class)
     {
-        if (false === $file = wincache_ucache_get($this->prefix.$class)) {
-            wincache_ucache_set($this->prefix.$class, $file = $this->decorated->findFile($class), 0);
+        $file = wincache_ucache_get($this->prefix.$class, $success);
+
+        if (!$success) {
+            wincache_ucache_set($this->prefix.$class, $file = $this->decorated->findFile($class) ?: null, 0);
         }
 
         return $file;
diff --git a/src/Symfony/Component/ClassLoader/XcacheClassLoader.php b/src/Symfony/Component/ClassLoader/XcacheClassLoader.php
index bf512273ef..11da39d6f3 100644
--- a/src/Symfony/Component/ClassLoader/XcacheClassLoader.php
+++ b/src/Symfony/Component/ClassLoader/XcacheClassLoader.php
@@ -126,7 +126,7 @@ class XcacheClassLoader
         if (xcache_isset($this->prefix.$class)) {
             $file = xcache_get($this->prefix.$class);
         } else {
-            $file = $this->decorated->findFile($class);
+            $file = $this->decorated->findFile($class) ?: null;
             xcache_set($this->prefix.$class, $file);
         }