diff --git a/pandas_alive/geocharts.py b/pandas_alive/geocharts.py
index c26055d..2dce2d8 100644
--- a/pandas_alive/geocharts.py
+++ b/pandas_alive/geocharts.py
@@ -6,6 +6,7 @@
 from typing import Mapping
 
 import attr
+import geopandas
 import matplotlib.dates as mdates
 import matplotlib.pyplot as plt
 import matplotlib.units as munits
@@ -184,9 +185,8 @@ def plot_geo_data(self, i: int, gdf: geopandas.GeoDataFrame) -> None:
                     contextily.add_basemap(self.ax)
 
             except ImportError:
-                import warnings
 
-                warnings.warn(
+                raise ModuleNotFoundError(
                     "Ensure contextily is installed for basemap functionality https://github.com/geopandas/contextily"
                 )