diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index 157987b9e..9d9583e55 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -475,8 +475,9 @@ EOF;
     protected function getIncludeFilesFile(array $files, Filesystem $filesystem, $basePath, $vendorPath, $vendorPathCode, $appBaseDirCode)
     {
         $filesCode = '';
-        foreach ($files as $functionFile) {
-            $filesCode .= '    '.$this->getPathCode($filesystem, $basePath, $vendorPath, $functionFile).",\n";
+        foreach ($files as $fileIdentifier => $functionFile) {
+            $filesCode .= '    ' . $fileIdentifier . ' => '
+                . $this->getPathCode($filesystem, $basePath, $vendorPath, $functionFile) . ",\n";
         }
 
         if (!$filesCode) {
@@ -649,8 +650,8 @@ REGISTER_LOADER;
         if ($useIncludeFiles) {
             $file .= <<<INCLUDE_FILES
         \$includeFiles = require __DIR__ . '/autoload_files.php';
-        foreach (\$includeFiles as \$file) {
-            composerRequire$suffix(\$file);
+        foreach (\$includeFiles as \$fileIdentifier => \$file) {
+            composerRequire$suffix(\$fileIdentifier, \$file);
         }
 
 
@@ -668,9 +669,17 @@ METHOD_FOOTER;
         return $file . <<<FOOTER
 }
 
-function composerRequire$suffix(\$file)
+function composerRequire$suffix(\$fileIdentifier, \$file)
 {
-    require \$file;
+    if (empty(\$GLOBALS['composerRequiredFiles'])) {
+        \$GLOBALS['composerRequiredFiles'] = array();
+    }
+
+    if (empty(\$GLOBALS['composerRequiredFiles'][\$fileIdentifier])) {
+        require \$file;
+
+        \$GLOBALS['composerRequiredFiles'][\$fileIdentifier] = true;
+    }
 }
 
 FOOTER;
@@ -742,7 +751,11 @@ FOOTER;
 
                     $relativePath = empty($installPath) ? (empty($path) ? '.' : $path) : $installPath.'/'.$path;
 
-                    if ($type === 'files' || $type === 'classmap') {
+                    if ($type === 'files') {
+                        $autoloads[var_export($this->getFileIdentifier($relativePath), true)]
+                            = $relativePath;
+                        continue;
+                    } elseif ($type === 'classmap') {
                         $autoloads[] = $relativePath;
                         continue;
                     }
@@ -755,6 +768,11 @@ FOOTER;
         return $autoloads;
     }
 
+    protected function getFileIdentifier($path)
+    {
+        return md5_file($path);
+    }
+
     /**
      * Sorts packages by dependency weight
      *
diff --git a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
index c88c555ef..a2894c639 100644
--- a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
+++ b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
@@ -1069,8 +1069,8 @@ EOF;
         $this->assertEquals($expectedNamespace, file_get_contents($vendorDir.'/composer/autoload_namespaces.php'));
         $this->assertEquals($expectedPsr4, file_get_contents($vendorDir.'/composer/autoload_psr4.php'));
         $this->assertEquals($expectedClassmap, file_get_contents($vendorDir.'/composer/autoload_classmap.php'));
-        $this->assertContains("\n    \$vendorDir . '/b/b/bootstrap.php',\n", file_get_contents($vendorDir.'/composer/autoload_files.php'));
-        $this->assertContains("\n    \$baseDir . '/test.php',\n", file_get_contents($vendorDir.'/composer/autoload_files.php'));
+        $this->assertContains("\$vendorDir . '/b/b/bootstrap.php',\n", file_get_contents($vendorDir.'/composer/autoload_files.php'));
+        $this->assertContains("\$baseDir . '/test.php',\n", file_get_contents($vendorDir.'/composer/autoload_files.php'));
     }
 
     public function testUpLevelRelativePaths()
@@ -1147,7 +1147,7 @@ EOF;
         $this->assertEquals($expectedNamespace, file_get_contents($this->vendorDir.'/composer/autoload_namespaces.php'));
         $this->assertEquals($expectedPsr4, file_get_contents($this->vendorDir.'/composer/autoload_psr4.php'));
         $this->assertEquals($expectedClassmap, file_get_contents($this->vendorDir.'/composer/autoload_classmap.php'));
-        $this->assertContains("\n    \$baseDir . '/../test.php',\n", file_get_contents($this->vendorDir.'/composer/autoload_files.php'));
+        $this->assertContains("\$baseDir . '/../test.php',\n", file_get_contents($this->vendorDir.'/composer/autoload_files.php'));
     }
 
     public function testEmptyPaths()
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_files.php b/tests/Composer/Test/Autoload/Fixtures/autoload_files.php
index 17225d047..9ffb4b7e2 100644
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_files.php
+++ b/tests/Composer/Test/Autoload/Fixtures/autoload_files.php
@@ -6,6 +6,6 @@ $vendorDir = dirname(dirname(__FILE__));
 $baseDir = dirname($vendorDir);
 
 return array(
-    $baseDir . '/foo.php',
-    $baseDir . '/bar.php',
+    '25b429360a61ca2629fdf9a4f484981c' => $baseDir . '/foo.php',
+    '524f65941cc9a0fa65ff0ec097ccde8a' => $baseDir . '/bar.php',
 );
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_files2.php b/tests/Composer/Test/Autoload/Fixtures/autoload_files2.php
index 13cb9ecb3..3b10ed004 100644
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_files2.php
+++ b/tests/Composer/Test/Autoload/Fixtures/autoload_files2.php
@@ -6,5 +6,5 @@ $vendorDir = dirname(dirname(__FILE__));
 $baseDir = dirname($vendorDir);
 
 return array(
-    $baseDir . '/devfiles/foo.php',
+    'fc1e99cd93a6aa58e3b1565e688bcd87' => $baseDir . '/devfiles/foo.php',
 );
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_files_functions.php b/tests/Composer/Test/Autoload/Fixtures/autoload_files_functions.php
index 6b6494b2c..502239a93 100644
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_files_functions.php
+++ b/tests/Composer/Test/Autoload/Fixtures/autoload_files_functions.php
@@ -6,9 +6,9 @@ $vendorDir = dirname(dirname(__FILE__));
 $baseDir = dirname($vendorDir);
 
 return array(
-    $vendorDir . '/a/a/test.php',
-    $vendorDir . '/b/b/test2.php',
-    $vendorDir . '/c/c/foo/bar/test3.php',
-    $vendorDir . '/c/c/foo/bar/test4.php',
-    $baseDir . '/root.php',
+    'b18a3c4a24b1dc69fdd96098e5c28e01' => $vendorDir . '/a/a/test.php',
+    '93797e35718fdafb825b1fe25c08a92c' => $vendorDir . '/b/b/test2.php',
+    'a57008eef928ced7c299bfea724d8441' => $vendorDir . '/c/c/foo/bar/test3.php',
+    '32e13a06a803ac6553a93454bcd3d2da' => $vendorDir . '/c/c/foo/bar/test4.php',
+    '504bb142db8acef729eeeb06b0aedec5' => $baseDir . '/root.php',
 );
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_files_target_dir.php b/tests/Composer/Test/Autoload/Fixtures/autoload_files_target_dir.php
index 17225d047..9ffb4b7e2 100644
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_files_target_dir.php
+++ b/tests/Composer/Test/Autoload/Fixtures/autoload_files_target_dir.php
@@ -6,6 +6,6 @@ $vendorDir = dirname(dirname(__FILE__));
 $baseDir = dirname($vendorDir);
 
 return array(
-    $baseDir . '/foo.php',
-    $baseDir . '/bar.php',
+    '25b429360a61ca2629fdf9a4f484981c' => $baseDir . '/foo.php',
+    '524f65941cc9a0fa65ff0ec097ccde8a' => $baseDir . '/bar.php',
 );
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_real_files_by_dependency.php b/tests/Composer/Test/Autoload/Fixtures/autoload_real_files_by_dependency.php
index 083070539..978077f55 100644
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_real_files_by_dependency.php
+++ b/tests/Composer/Test/Autoload/Fixtures/autoload_real_files_by_dependency.php
@@ -41,15 +41,23 @@ class ComposerAutoloaderInitFilesAutoloadOrder
         $loader->register(true);
 
         $includeFiles = require __DIR__ . '/autoload_files.php';
-        foreach ($includeFiles as $file) {
-            composerRequireFilesAutoloadOrder($file);
+        foreach ($includeFiles as $fileIdentifier => $file) {
+            composerRequireFilesAutoloadOrder($fileIdentifier, $file);
         }
 
         return $loader;
     }
 }
 
-function composerRequireFilesAutoloadOrder($file)
+function composerRequireFilesAutoloadOrder($fileIdentifier, $file)
 {
-    require $file;
+    if (empty($GLOBALS['composerRequiredFiles'])) {
+        $GLOBALS['composerRequiredFiles'] = array();
+    }
+
+    if (empty($GLOBALS['composerRequiredFiles'][$fileIdentifier])) {
+        require $file;
+
+        $GLOBALS['composerRequiredFiles'][$fileIdentifier] = true;
+    }
 }
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_real_functions.php b/tests/Composer/Test/Autoload/Fixtures/autoload_real_functions.php
index 1c0154964..cb9ab3e73 100644
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_real_functions.php
+++ b/tests/Composer/Test/Autoload/Fixtures/autoload_real_functions.php
@@ -41,15 +41,23 @@ class ComposerAutoloaderInitFilesAutoload
         $loader->register(true);
 
         $includeFiles = require __DIR__ . '/autoload_files.php';
-        foreach ($includeFiles as $file) {
-            composerRequireFilesAutoload($file);
+        foreach ($includeFiles as $fileIdentifier => $file) {
+            composerRequireFilesAutoload($fileIdentifier, $file);
         }
 
         return $loader;
     }
 }
 
-function composerRequireFilesAutoload($file)
+function composerRequireFilesAutoload($fileIdentifier, $file)
 {
-    require $file;
+    if (empty($GLOBALS['composerRequiredFiles'])) {
+        $GLOBALS['composerRequiredFiles'] = array();
+    }
+
+    if (empty($GLOBALS['composerRequiredFiles'][$fileIdentifier])) {
+        require $file;
+
+        $GLOBALS['composerRequiredFiles'][$fileIdentifier] = true;
+    }
 }
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_real_include_path.php b/tests/Composer/Test/Autoload/Fixtures/autoload_real_include_path.php
index 65ba6819e..e93179572 100644
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_real_include_path.php
+++ b/tests/Composer/Test/Autoload/Fixtures/autoload_real_include_path.php
@@ -65,7 +65,15 @@ class ComposerAutoloaderInitIncludePath
     }
 }
 
-function composerRequireIncludePath($file)
+function composerRequireIncludePath($fileIdentifier, $file)
 {
-    require $file;
+    if (empty($GLOBALS['composerRequiredFiles'])) {
+        $GLOBALS['composerRequiredFiles'] = array();
+    }
+
+    if (empty($GLOBALS['composerRequiredFiles'][$fileIdentifier])) {
+        require $file;
+
+        $GLOBALS['composerRequiredFiles'][$fileIdentifier] = true;
+    }
 }
diff --git a/tests/Composer/Test/Autoload/Fixtures/autoload_real_target_dir.php b/tests/Composer/Test/Autoload/Fixtures/autoload_real_target_dir.php
index dc786f767..7fc42d325 100644
--- a/tests/Composer/Test/Autoload/Fixtures/autoload_real_target_dir.php
+++ b/tests/Composer/Test/Autoload/Fixtures/autoload_real_target_dir.php
@@ -43,8 +43,8 @@ class ComposerAutoloaderInitTargetDir
         $loader->register(true);
 
         $includeFiles = require __DIR__ . '/autoload_files.php';
-        foreach ($includeFiles as $file) {
-            composerRequireTargetDir($file);
+        foreach ($includeFiles as $fileIdentifier => $file) {
+            composerRequireTargetDir($fileIdentifier, $file);
         }
 
         return $loader;
@@ -69,7 +69,15 @@ class ComposerAutoloaderInitTargetDir
     }
 }
 
-function composerRequireTargetDir($file)
+function composerRequireTargetDir($fileIdentifier, $file)
 {
-    require $file;
+    if (empty($GLOBALS['composerRequiredFiles'])) {
+        $GLOBALS['composerRequiredFiles'] = array();
+    }
+
+    if (empty($GLOBALS['composerRequiredFiles'][$fileIdentifier])) {
+        require $file;
+
+        $GLOBALS['composerRequiredFiles'][$fileIdentifier] = true;
+    }
 }