diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6580b577..b1201771 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,9 @@ All notable changes to this project will be documented in this file.
 
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+### v0.18.2
+* Fixed duplicate index check in `_lat_lons_from_geojson` where `s[0]` was validated twice instead of checking both `s[0]` and `s[1]`
+
 ### v0.18.1
 * Added optional `seed` parameter to `sample_proportions()` for reproducible results
 * Added optional `seed` parameter to `proportions_from_distribution()` for reproducible results
diff --git a/datascience/maps.py b/datascience/maps.py
index 652491b3..6a36c27b 100644
--- a/datascience/maps.py
+++ b/datascience/maps.py
@@ -904,7 +904,7 @@ def _lat_lons_from_geojson(s):
 
     GeoJSON coordinates are always stored in (longitude, latitude) order.
     """
-    if len(s) >= 2 and isinstance(s[0], _number) and isinstance(s[0], _number):
+    if len(s) >= 2 and isinstance(s[0], _number) and isinstance(s[1], _number):
         lat, lon = s[1], s[0]
         return [(lat, lon)]
     else: