diff --git a/src/Composer/Downloader/GitDownloader.php b/src/Composer/Downloader/GitDownloader.php
index 35f6aa754..beccd55ec 100644
--- a/src/Composer/Downloader/GitDownloader.php
+++ b/src/Composer/Downloader/GitDownloader.php
@@ -73,6 +73,10 @@ class GitDownloader extends VcsDownloader
      */
     public function getLocalChanges($path)
     {
+        if (!is_dir($path.'/.git')) {
+            return;
+        }
+
         $command = sprintf('cd %s && git status --porcelain --untracked-files=no', escapeshellarg($path));
         if (0 !== $this->process->execute($command, $output)) {
             throw new \RuntimeException('Failed to execute ' . $command . "\n\n" . $this->process->getErrorOutput());
diff --git a/src/Composer/Downloader/HgDownloader.php b/src/Composer/Downloader/HgDownloader.php
index fc66e40eb..a3ee59788 100644
--- a/src/Composer/Downloader/HgDownloader.php
+++ b/src/Composer/Downloader/HgDownloader.php
@@ -54,6 +54,10 @@ class HgDownloader extends VcsDownloader
      */
     public function getLocalChanges($path)
     {
+        if (!is_dir($path.'/.hg')) {
+            return;
+        }
+
         $this->process->execute(sprintf('cd %s && hg st', escapeshellarg($path)), $output);
 
         return trim($output) ?: null;
diff --git a/src/Composer/Downloader/SvnDownloader.php b/src/Composer/Downloader/SvnDownloader.php
index c828337f3..82f2bd336 100644
--- a/src/Composer/Downloader/SvnDownloader.php
+++ b/src/Composer/Downloader/SvnDownloader.php
@@ -50,6 +50,10 @@ class SvnDownloader extends VcsDownloader
      */
     public function getLocalChanges($path)
     {
+        if (!is_dir($path.'/.svn')) {
+            return;
+        }
+
         $this->process->execute('svn status --ignore-externals', $output, $path);
 
         return preg_match('{^ *[^X ] +}m', $output) ? $output : null;