diff --git a/PVE/Storage/GlusterfsPlugin.pm b/PVE/Storage/GlusterfsPlugin.pm
index 2dd414d..5ec2f42 100644
--- a/PVE/Storage/GlusterfsPlugin.pm
+++ b/PVE/Storage/GlusterfsPlugin.pm
@@ -228,7 +228,7 @@ sub clone_image {
     my $volumepath = "gluster://$server/$glustervolume/images/$vmid/$name";
 
     my $cmd = ['/usr/bin/qemu-img', 'create', '-b', "../$basevmid/$basename",
-	       '-f', 'qcow2', $volumepath];
+	       '-F', $format, '-f', 'qcow2', $volumepath];
 
     run_command($cmd, errmsg => "unable to create image");
 
diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
index d7136a1..4a10a1f 100644
--- a/PVE/Storage/Plugin.pm
+++ b/PVE/Storage/Plugin.pm
@@ -708,7 +708,7 @@ sub clone_image {
 	local $CWD = $imagedir;
 
 	my $cmd = ['/usr/bin/qemu-img', 'create', '-b', "../$basevmid/$basename",
-		   '-f', 'qcow2', $path];
+		   '-F', $format, '-f', 'qcow2', $path];
 
 	run_command($cmd);
     };