diff --git a/SalishSeaTools/salishsea_tools/geo_tools.py b/SalishSeaTools/salishsea_tools/geo_tools.py
index ea461dcd..b203ed57 100644
--- a/SalishSeaTools/salishsea_tools/geo_tools.py
+++ b/SalishSeaTools/salishsea_tools/geo_tools.py
@@ -60,7 +60,7 @@ def haversine(lon1, lat1, lon2, lat2):
     dlat = lat2 - lat1
     a = np.sin(dlat / 2) ** 2 + np.cos(lat1) * np.cos(lat2) * np.sin(dlon / 2) ** 2
     c = 2 * np.arcsin(np.sqrt(a))
-    km = 6367 * c
+    km = 6371.229 * c
     return km