Error in IE

[GeospatialPython]

Thank you for the great plug-in. It works everywhere I've tested it except IE 11 (V. 11.0.9600.18665).

I get the same error in both my leaflet application and the plugin's included example.

Execution stops at Line 48: L.grids.distance.imperial().addTo(map);

Error: "Unable to get property 'distance' of undefined or null reference".

Any ideas?