diff --git a/src/Composer/IO/ConsoleIO.php b/src/Composer/IO/ConsoleIO.php
index 491a6b7fb..78b271356 100644
--- a/src/Composer/IO/ConsoleIO.php
+++ b/src/Composer/IO/ConsoleIO.php
@@ -97,12 +97,14 @@ class ConsoleIO extends BaseIO
     {
         if (null !== $this->startTime) {
             $messages = (array) $messages;
-            $messages[0] = sprintf(
-                '[%.1fMB/%.2fs] %s',
-                memory_get_usage() / 1024 / 1024,
-                microtime(true) - $this->startTime,
-                $messages[0]
-            );
+            $messages = array_map(function (&$message) {
+                return sprintf(
+                    '[%.1fMB/%.2fs] %s',
+                    memory_get_usage() / 1024 / 1024,
+                    microtime(true) - $this->startTime,
+                    $message
+                );
+            }, $messages);
         }
         $this->output->write($messages, $newline);
         $this->lastMessage = join($newline ? "\n" : '', (array) $messages);
diff --git a/tests/Composer/Test/IO/ConsoleIOTest.php b/tests/Composer/Test/IO/ConsoleIOTest.php
index 6ce95b0ac..8c9fad5fa 100644
--- a/tests/Composer/Test/IO/ConsoleIOTest.php
+++ b/tests/Composer/Test/IO/ConsoleIOTest.php
@@ -49,6 +49,30 @@ class ConsoleIOTest extends TestCase
         $consoleIO->write('some information about something', false);
     }
 
+    public function testWriteWithMultipleLineStringWhenDebugging()
+    {
+        $inputMock = $this->getMock('Symfony\Component\Console\Input\InputInterface');
+        $outputMock = $this->getMock('Symfony\Component\Console\Output\OutputInterface');
+        $outputMock->expects($this->once())
+            ->method('write')
+            ->with(
+                $this->callback(function($messages){
+                    $this->assertRegExp("[(.*)/(.*) First line]", $messages[0]);
+                    $this->assertRegExp("[(.*)/(.*) Second line]", $messages[1]);
+                    return true;
+                }),
+                $this->equalTo(false)
+            );
+        $helperMock = $this->getMock('Symfony\Component\Console\Helper\HelperSet');
+
+        $consoleIO = new ConsoleIO($inputMock, $outputMock, $helperMock);
+        $startTime = microtime(true);
+        $consoleIO->enableDebugging($startTime);
+
+        $example = explode('\n', 'First line\nSecond lines');
+        $consoleIO->write($example, false);
+    }
+
     public function testOverwrite()
     {
         $inputMock = $this->getMock('Symfony\Component\Console\Input\InputInterface');