diff --git a/src/Composer/Util/Git.php b/src/Composer/Util/Git.php
index 34b686d9a..4888c17bd 100644
--- a/src/Composer/Util/Git.php
+++ b/src/Composer/Util/Git.php
@@ -177,6 +177,11 @@ class Git
             unset($_SERVER['GIT_WORK_TREE']);
         }
 
+        // Run processes with predictable LANGUAGE
+        if (getenv('LANGUAGE') !== 'C') {
+            putenv('LANGUAGE=C');
+        }
+
         // clean up env for OSX, see https://github.com/composer/composer/issues/2146#issuecomment-35478940
         putenv("DYLD_LIBRARY_PATH");
         unset($_SERVER['DYLD_LIBRARY_PATH']);
diff --git a/src/Composer/Util/ProcessExecutor.php b/src/Composer/Util/ProcessExecutor.php
index e7cfa3dcc..38f5bba00 100644
--- a/src/Composer/Util/ProcessExecutor.php
+++ b/src/Composer/Util/ProcessExecutor.php
@@ -56,7 +56,7 @@ class ProcessExecutor
 
         $this->captureOutput = count(func_get_args()) > 1;
         $this->errorOutput = null;
-        $process = new Process($command, $cwd, array_replace($_ENV, $_SERVER, array('LANGUAGE' => 'C')), null, static::getTimeout());
+        $process = new Process($command, $cwd, null, null, static::getTimeout());
 
         $callback = is_callable($output) ? $output : array($this, 'outputHandler');
         $process->run($callback);