diff --git a/pygal/view.py b/pygal/view.py
index 4821239..13664a3 100644
--- a/pygal/view.py
+++ b/pygal/view.py
@@ -112,7 +112,7 @@ class Box(object):
     @ymax.setter
     def ymax(self, value):
         """Y maximum setter"""
-        if value:
+        if value or self.ymin:
             self._ymax = value
 
     @property