diff --git a/fixtures/composer.json b/fixtures/composer.json
new file mode 100644
index 00000000..6ec2e922
--- /dev/null
+++ b/fixtures/composer.json
@@ -0,0 +1,6 @@
+{
+    "require": {
+        "example/example-version": "1.0.7",
+        "example/example-reference": "dev-master"
+    }
+}
\ No newline at end of file
diff --git a/fixtures/composer.lock b/fixtures/composer.lock
new file mode 100644
index 00000000..6d84154b
--- /dev/null
+++ b/fixtures/composer.lock
@@ -0,0 +1,55 @@
+{
+    "_readme": [
+        "This is a mock lock file for composer"
+    ],
+    "content-hash": "3da868eb11c9a94f957057f73d2936ef",
+    "packages": [
+        {
+            "name": "example/example-version",
+            "version": "1.0.7",
+            "source": {
+                "type": "git",
+                "url": "https://example.com",
+                "reference": "b17e6153cb7f33c7e44eb59578dc12eee5dc8e12"
+            },
+            "require": {},
+            "require-dev": {},
+            "suggest": {},
+            "type": "library",
+            "extra": {},
+            "autoload": {},
+            "license": [],
+            "authors": [],
+            "description": "",
+            "keywords": [],
+            "time": "2017-03-06T11:59:08+00:00"
+        },
+        {
+            "name": "example/example-reference",
+            "version": "1.0.7",
+            "source": {
+                "type": "git",
+                "url": "https://example.com",
+                "reference": "b17e6153cb7f33c7e44eb59578dc12eee5dc8e12"
+            },
+            "require": {},
+            "require-dev": {},
+            "suggest": {},
+            "type": "library",
+            "extra": {},
+            "autoload": {},
+            "license": [],
+            "authors": [],
+            "description": "",
+            "keywords": [],
+            "time": "2017-03-06T11:59:08+00:00"
+        }
+    ],
+    "packages-dev": [],
+    "aliases": [],
+    "minimum-stability": "dev",
+    "prefer-stable": true,
+    "prefer-lowest": false,
+    "platform": {},
+    "platform-dev": []
+}
diff --git a/fixtures/vendor/example/example-reference/test.php b/fixtures/vendor/example/example-reference/test.php
new file mode 100644
index 00000000..b3d9bbc7
--- /dev/null
+++ b/fixtures/vendor/example/example-reference/test.php
@@ -0,0 +1 @@
+<?php
diff --git a/fixtures/vendor/example/example-version/test.php b/fixtures/vendor/example/example-version/test.php
new file mode 100644
index 00000000..50cce95b
--- /dev/null
+++ b/fixtures/vendor/example/example-version/test.php
@@ -0,0 +1,3 @@
+<?php
+
+
diff --git a/src/Indexer.php b/src/Indexer.php
index 34ad618f..45584317 100644
--- a/src/Indexer.php
+++ b/src/Indexer.php
@@ -149,15 +149,26 @@ public function index(): Promise
                 $cacheKey = null;
                 $index = null;
                 foreach (array_merge($this->composerLock->packages, $this->composerLock->{'packages-dev'}) as $package) {
-                    // Check if package name matches and version is absolute
-                    // Dynamic constraints are not cached, because they can change every time
+                    if ($package->name !== $packageName) {
+                        continue;
+                    }
+                    // Check if package can be cached.
                     $packageVersion = ltrim($package->version, 'v');
-                    if ($package->name === $packageName && strpos($packageVersion, 'dev') === false) {
+                    // If package is anchored to a version
+                    if (strpos($packageVersion, 'dev') === false) {
                         $packageKey = $packageName . ':' . $packageVersion;
                         $cacheKey = self::CACHE_VERSION . ':' . $packageKey;
                         // Check cache
                         $index = yield $this->cache->get($cacheKey);
                         break;
+
+                    // If package is checked out
+                    } else if (isset($package->source->reference)) {
+                        $packageKey = $packageName . ':' . $package->source->reference;
+                        $cacheKey = self::CACHE_VERSION . ':' . $packageKey;
+                        // Check cache
+                        $index = yield $this->cache->get($cacheKey);
+                        break;
                     }
                 }
                 if ($index !== null) {
diff --git a/tests/LanguageServerTest.php b/tests/LanguageServerTest.php
index fb52ef64..79451975 100644
--- a/tests/LanguageServerTest.php
+++ b/tests/LanguageServerTest.php
@@ -53,12 +53,18 @@ public function testIndexingWithDirectFileAccess()
         $promise = new Promise;
         $input = new MockProtocolStream;
         $output = new MockProtocolStream;
-        $output->on('message', function (Message $msg) use ($promise) {
+        $cacheVersionCalled = false;
+        $cacheReferenceCalled = false;
+        $output->on('message', function (Message $msg) use ($promise, &$cacheVersionCalled, &$cacheReferenceCalled) {
             if ($msg->body->method === 'window/logMessage' && $promise->state === Promise::PENDING) {
                 if ($msg->body->params->type === MessageType::ERROR) {
                     $promise->reject(new Exception($msg->body->params->message));
-                } else if (strpos($msg->body->params->message, 'All 27 PHP files parsed') !== false) {
+                } else if (preg_match('/All [0-9]+ PHP files parsed/', $msg->body->params->message)) {
                     $promise->fulfill();
+                } else if (preg_match('#(Storing|Restored) example/example-version:.* (in|from) cache#', $msg->body->params->message)) {
+                    $cacheVersionCalled = true;
+                } else if (preg_match('#(Storing|Restored) example/example-reference:.* (in|from) cache#', $msg->body->params->message)) {
+                    $cacheReferenceCalled = true;
                 }
             }
         });
@@ -66,6 +72,8 @@ public function testIndexingWithDirectFileAccess()
         $capabilities = new ClientCapabilities;
         $server->initialize($capabilities, realpath(__DIR__ . '/../fixtures'), getmypid());
         $promise->wait();
+        $this->assertTrue($cacheVersionCalled);
+        $this->assertTrue($cacheReferenceCalled);
     }
 
     public function testIndexingWithFilesAndContentRequests()
@@ -103,7 +111,7 @@ public function testIndexingWithFilesAndContentRequests()
                     if ($promise->state === Promise::PENDING) {
                         $promise->reject(new Exception($msg->body->params->message));
                     }
-                } else if (strpos($msg->body->params->message, 'All 27 PHP files parsed') !== false) {
+                } else if (preg_match('/All [0-9]+ PHP files parsed/', $msg->body->params->message)) {
                     $promise->fulfill();
                 }
             }