diff --git a/bayesian_filters/hinfinity/hinfinity_filter.py b/bayesian_filters/hinfinity/hinfinity_filter.py
index 7513161..bf5043e 100644
--- a/bayesian_filters/hinfinity/hinfinity_filter.py
+++ b/bayesian_filters/hinfinity/hinfinity_filter.py
@@ -100,7 +100,7 @@ def update(self, z):
             measurement for this update.
         """
 
-        if z is None:
+        if z is None or z is np.ma.masked:
             return
 
         # rename for readability and a tiny extra bit of speed