diff --git a/FSCalendar/FSCalendarTransitionCoordinator.m b/FSCalendar/FSCalendarTransitionCoordinator.m
index 6468e8d6..0765f5ec 100644
--- a/FSCalendar/FSCalendarTransitionCoordinator.m
+++ b/FSCalendar/FSCalendarTransitionCoordinator.m
@@ -136,7 +136,7 @@ - (void)scopeTransitionDidUpdate:(UIPanGestureRecognizer *)panGesture
         CGFloat maxTranslation = ABS(CGRectGetHeight(self.transitionAttributes.targetBounds) - CGRectGetHeight(self.transitionAttributes.sourceBounds));
         translation = MIN(maxTranslation, translation);
         translation = MAX(0, translation);
-        CGFloat progress = translation/maxTranslation;
+        CGFloat progress = maxTranslation==0? 0 : translation/maxTranslation;
         progress;
     });
     [self performAlphaAnimationWithProgress:progress];