diff --git a/src/Composer/Command/DiagnoseCommand.php b/src/Composer/Command/DiagnoseCommand.php
index a288109c7..f0bab63a7 100644
--- a/src/Composer/Command/DiagnoseCommand.php
+++ b/src/Composer/Command/DiagnoseCommand.php
@@ -177,17 +177,12 @@ EOT
 
         $finder = new ExecutableFinder;
         $hasSystemUnzip = (bool) $finder->find('unzip');
-        if (Platform::isWindows()) {
-            $hasSystem7zip = (bool) $finder->find('7z', null, array('C:\Program Files\7-Zip'));
-            $windows7z = ', ' . ($hasSystem7zip ? '<comment>7-Zip present</comment>' : '<comment>7-Zip not available</comment>');
-        } else {
-            $windows7z = '';
-        }
+        $hasSystem7zip = (bool) $finder->find('7z', null, array('C:\Program Files\7-Zip'));
 
         $io->write(
             'zip: ' . (extension_loaded('zip') ? '<comment>extension present</comment>' : '<comment>extension not loaded</comment>')
             . ', ' . ($hasSystemUnzip ? '<comment>unzip present</comment>' : '<comment>unzip not available</comment>')
-            . $windows7z
+            . ', ' . ($hasSystem7zip ? '<comment>7-Zip present</comment>' : '<comment>7-Zip not available</comment>')
         );
 
         return $this->exitCode;
diff --git a/src/Composer/Downloader/ZipDownloader.php b/src/Composer/Downloader/ZipDownloader.php
index 4475c5e8f..fd0b93a4a 100644
--- a/src/Composer/Downloader/ZipDownloader.php
+++ b/src/Composer/Downloader/ZipDownloader.php
@@ -46,6 +46,9 @@ class ZipDownloader extends ArchiveDownloader
             if ($cmd = $finder->find('unzip')) {
                 self::$unzipCommands[] = array('unzip', ProcessExecutor::escape($cmd).' -qq %s -d %s');
             }
+            if (!Platform::isWindows() && ($cmd = $finder->find('7z'))) { // 7z linux/macOS support is only used if unzip is not present
+                self::$unzipCommands[] = array('7z', ProcessExecutor::escape($cmd).' x -bb0 -y %s -o%s');
+            }
         }
 
         if (null === self::$hasZipArchive) {