diff --git a/kivy_garden/mapview/mbtsource.py b/kivy_garden/mapview/mbtsource.py
index e90f87a..44d4aca 100644
--- a/kivy_garden/mapview/mbtsource.py
+++ b/kivy_garden/mapview/mbtsource.py
@@ -39,9 +39,9 @@ def __init__(self, filename, **kwargs):
         cx = cy = 0.0
         cz = 5
         if "bounds" in metadata:
-            self.bounds = bounds = map(float, metadata["bounds"].split(","))
+            self.bounds = bounds = tuple(map(float, metadata["bounds"].split(",")))
         if "center" in metadata:
-            cx, cy, cz = map(float, metadata["center"].split(","))
+            cx, cy, cz = tuple(map(float, metadata["center"].split(",")))
         elif self.bounds:
             cx = (bounds[2] + bounds[0]) / 2.0
             cy = (bounds[3] + bounds[1]) / 2.0