diff --git a/include/FileSystem.h b/include/FileSystem.h
index bbad470e..df3991d4 100644
--- a/include/FileSystem.h
+++ b/include/FileSystem.h
@@ -79,12 +79,13 @@ struct FS
 	Support online_read;        // Can and how to read sector usage while active
 	Support online_grow;
 	Support online_shrink;
+	Support online_write_label;
 
 	FS(FSType fstype_ = FS_UNSUPPORTED) : fstype(fstype_)
 	{
 		busy = read = read_label = write_label = read_uuid = write_uuid = create =
 		create_with_label = grow = shrink = move = check = copy = remove = online_read =
-		online_grow = online_shrink = NONE;
+		online_grow = online_shrink = online_write_label = NONE;
 	}
 };
 
diff --git a/src/GParted_Core.cc b/src/GParted_Core.cc
index f7ac970c..27eb6a1d 100644
--- a/src/GParted_Core.cc
+++ b/src/GParted_Core.cc
@@ -2053,7 +2053,9 @@ bool GParted_Core::label_filesystem( const Partition & partition, OperationDetai
 
 	bool succes = false ;
 	FileSystem* p_filesystem = NULL ;
-	switch (get_fs(partition.fstype).write_label)
+	const FS& fs_cap = get_fs(partition.fstype);
+	FS::Support support = (partition.busy) ? fs_cap.online_write_label : fs_cap.write_label;
+	switch (support)
 	{
 		case FS::EXTERNAL:
 			succes =    (p_filesystem = get_filesystem_object(partition.fstype))
diff --git a/src/Win_GParted.cc b/src/Win_GParted.cc
index f2d1975a..75ea445e 100644
--- a/src/Win_GParted.cc
+++ b/src/Win_GParted.cc
@@ -1299,6 +1299,14 @@ void Win_GParted::set_valid_operations()
 	}
 #endif
 
+	// Allow labelling of mounted file systems that support it.
+	if (selected_filesystem.busy                    &&
+	    selected_partition_ptr->status == STAT_REAL &&
+	    fs_cap.online_write_label                     )
+	{
+		allow_label_filesystem(true);
+	}
+
 	// Only unmount/swapoff/VG deactivate or online actions allowed if busy
 	if ( selected_filesystem.busy )
 		return ;
diff --git a/src/btrfs.cc b/src/btrfs.cc
index f3b7bce3..b8c72086 100644
--- a/src/btrfs.cc
+++ b/src/btrfs.cc
@@ -66,6 +66,7 @@ FS btrfs::get_filesystem_support()
 		fs .read_uuid = FS::EXTERNAL ;
 		fs.check = FS::EXTERNAL;
 		fs.write_label = FS::EXTERNAL;
+		fs.online_write_label = FS::EXTERNAL;
 
 		//Resizing of btrfs requires mount, umount and kernel
 		//  support as well as btrfs filesystem resize
@@ -261,13 +262,25 @@ void btrfs::set_used_sectors( Partition & partition )
 	}
 }
 
+
 bool btrfs::write_label( const Partition & partition, OperationDetail & operationdetail )
 {
-	return ! execute_command( "btrfs filesystem label " + Glib::shell_quote( partition.get_path() ) +
-	                          " " + Glib::shell_quote( partition.get_filesystem_label() ),
-	                          operationdetail, EXEC_CHECK_STATUS );
+	// Use the mount point when labelling a mounted btrfs, or block device containing
+	// the unmounted btrfs.
+	//     btrfs filesystem label '/dev/PTN' 'NEWLABEL'
+	//     btrfs filesystem label '/MNTPNT' 'NEWLABEL'
+	Glib::ustring path;
+	if (partition.busy)
+		path = partition.get_mountpoint();
+	else
+		path = partition.get_path();
+
+	return ! execute_command("btrfs filesystem label " + Glib::shell_quote(path) +
+	                         " " + Glib::shell_quote(partition.get_filesystem_label()),
+	                         operationdetail, EXEC_CHECK_STATUS);
 }
 
+
 bool btrfs::resize( const Partition & partition_new, OperationDetail & operationdetail, bool fill_partition )
 {
 	bool success = true ;