diff --git a/pandora/item/timelines.py b/pandora/item/timelines.py
index 167895f5..cbc44b82 100644
--- a/pandora/item/timelines.py
+++ b/pandora/item/timelines.py
@@ -117,10 +117,12 @@ def join_tiles(source_paths, target_path):
             mode = info['mode']
             source_files[mode].append(path + info['file'])
     modes = [m for m in modes if source_files[m]]
-    for f in source_files[modes[0]]:
-        width = Image.open(f).size[0]
-        durations[i] += width / fps
-        frame_n += width
+    for i, path in enumerate(source_paths):
+        for f in source_files[modes[0]]:
+            if f.startswith(path):
+                width = Image.open(f).size[0]
+                durations[i] += width / fps
+                frame_n += width
     large_tile_n = int(math.ceil(frame_n / large_tile_w)) 
     large_tile_last_w = frame_n % large_tile_w or 60
     small_tile_n = int(math.ceil(frame_n / fps / small_tile_w))