diff --git a/core/geo_utils.py b/core/geo_utils.py
index 7d69c81..ce0cbf2 100644
--- a/core/geo_utils.py
+++ b/core/geo_utils.py
@@ -4,6 +4,7 @@ from math import floor
 
 import geopandas
 from pyproj import Transformer
+from shapely import prepare
 from shapely.geometry import Point, Polygon
 
 TRANSFORMER_OS_GRID_TO_WGS84 = Transformer.from_crs("EPSG:27700", "EPSG:4326")
@@ -12,15 +13,28 @@ TRANSFORMER_CI_UTM_GRID_TO_WGS84 = Transformer.from_crs("+proj=utm +zone=30 +ell
 
 cq_zone_data = geopandas.GeoDataFrame.from_features(geopandas.read_file("datafiles/cqzones.geojson"))
 itu_zone_data = geopandas.GeoDataFrame.from_features(geopandas.read_file("datafiles/ituzones.geojson"))
-
+for idx in cq_zone_data.index:
+    prepare(cq_zone_data.at[idx, 'geometry'])
+for idx in itu_zone_data.index:
+    prepare(itu_zone_data.at[idx, 'geometry'])
 
 # Finds out which CQ zone a lat/lon point is in.
 def lat_lon_to_cq_zone(lat, lon):
+    lon = ((lon + 180) % 360) - 180
     for index, row in cq_zone_data.iterrows():
         polygon = Polygon(row["geometry"])
         test_point = Point(lon, lat)
         if polygon.contains(test_point):
             return int(row["name"])
+
+        # Might have problems around the antemeridian, so if we didn't find a match, try offsetting the point by + or -
+        # 360 degrees longitude to try the other side of the Earth
+        if lon < 0:
+            test_point = Point(lon + 360, lat)
+        else:
+            test_point = Point(lon - 360, lat)
+        if polygon.contains(test_point):
+            return int(row["name"])
     return None