diff --git a/src/Composer/Compiler.php b/src/Composer/Compiler.php
index 27b1f4816..2c763d053 100644
--- a/src/Composer/Compiler.php
+++ b/src/Composer/Compiler.php
@@ -193,6 +193,7 @@ class Compiler
             $content = str_replace('@package_version@', $this->version, $content);
             $content = str_replace('@package_branch_alias_version@', $this->branchAliasVersion, $content);
             $content = str_replace('@release_date@', $this->versionDate->format('Y-m-d H:i:s'), $content);
+            $content = preg_replace('{SOURCE_VERSION = \'[^\']+\';}', 'SOURCE_VERSION = \'\';', $content);
         }
 
         $phar->addFromString($path, $content);
diff --git a/src/Composer/Composer.php b/src/Composer/Composer.php
index a3972f44f..7b60b28af 100644
--- a/src/Composer/Composer.php
+++ b/src/Composer/Composer.php
@@ -29,9 +29,46 @@ use Composer\Package\Archiver\ArchiveManager;
  */
 class Composer
 {
+    /*
+     * Examples of the following constants in the various configurations they can be in
+     *
+     * releases (phar):
+     * const VERSION = '1.8.2';
+     * const BRANCH_ALIAS_VERSION = '';
+     * const RELEASE_DATE = '2019-01-29 15:00:53';
+     * const SOURCE_VERSION = '';
+     *
+     * snapshot builds (phar):
+     * const VERSION = 'd3873a05650e168251067d9648845c220c50e2d7';
+     * const BRANCH_ALIAS_VERSION = '1.9-dev';
+     * const RELEASE_DATE = '2019-02-20 07:43:56';
+     * const SOURCE_VERSION = '';
+     *
+     * source (git clone):
+     * const VERSION = '@package_version@';
+     * const BRANCH_ALIAS_VERSION = '@package_branch_alias_version@';
+     * const RELEASE_DATE = '@release_date@';
+     * const SOURCE_VERSION = '1.8-dev+source';
+     */
     const VERSION = '@package_version@';
     const BRANCH_ALIAS_VERSION = '@package_branch_alias_version@';
     const RELEASE_DATE = '@release_date@';
+    const SOURCE_VERSION = '1.8-dev+source';
+
+    public static function getVersion()
+    {
+        // no replacement done, this must be a source checkout
+        if (self::VERSION === '@package_version'.'@') {
+            return self::SOURCE_VERSION;
+        }
+
+        // we have a branch alias and version is a commit id, this must be a snapshot build
+        if (self::BRANCH_ALIAS_VERSION !== '' && preg_match('{^[a-f0-9]{40}$}', self::VERSION)) {
+            return self::BRANCH_ALIAS_VERSION.'+'.self::VERSION;
+        }
+
+        return self::VERSION;
+    }
 
     /**
      * @var Package\RootPackageInterface
diff --git a/src/Composer/Console/Application.php b/src/Composer/Console/Application.php
index ccf83c943..a829ac38a 100644
--- a/src/Composer/Console/Application.php
+++ b/src/Composer/Console/Application.php
@@ -89,7 +89,7 @@ class Application extends BaseApplication
 
         $this->io = new NullIO();
 
-        parent::__construct('Composer', Composer::VERSION);
+        parent::__construct('Composer', Composer::getVersion());
     }
 
     /**
@@ -181,7 +181,7 @@ class Application extends BaseApplication
         if (!$isProxyCommand) {
             $io->writeError(sprintf(
                 'Running %s (%s) with %s on %s',
-                Composer::VERSION,
+                Composer::getVersion(),
                 Composer::RELEASE_DATE,
                 defined('HHVM_VERSION') ? 'HHVM '.HHVM_VERSION : 'PHP '.PHP_VERSION,
                 function_exists('php_uname') ? php_uname('s') . ' / ' . php_uname('r') : 'Unknown OS'
@@ -425,7 +425,7 @@ class Application extends BaseApplication
      */
     public function getLongVersion()
     {
-        if (Composer::BRANCH_ALIAS_VERSION) {
+        if (Composer::BRANCH_ALIAS_VERSION && Composer::BRANCH_ALIAS_VERSION !== '@package_branch_alias_version'.'@') {
             return sprintf(
                 '<info>%s</info> version <comment>%s (%s)</comment> %s',
                 $this->getName(),
diff --git a/src/Composer/Util/StreamContextFactory.php b/src/Composer/Util/StreamContextFactory.php
index 8dfd6624a..da3e578bd 100644
--- a/src/Composer/Util/StreamContextFactory.php
+++ b/src/Composer/Util/StreamContextFactory.php
@@ -142,7 +142,7 @@ final class StreamContextFactory
         if (!isset($options['http']['header']) || false === stripos(implode('', $options['http']['header']), 'user-agent')) {
             $options['http']['header'][] = sprintf(
                 'User-Agent: Composer/%s (%s; %s; %s%s)',
-                Composer::VERSION === '@package_version@' ? 'source' : Composer::VERSION,
+                Composer::getVersion(),
                 function_exists('php_uname') ? php_uname('s') : 'Unknown',
                 function_exists('php_uname') ? php_uname('r') : 'Unknown',
                 $phpVersion,