diff --git a/HISTORY.rst b/HISTORY.rst
index db147f94d..333b91975 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -100,6 +100,10 @@ Unreleased Changes
     * Fixed a bug where the model incorrectly raised an error if the
       biophysical table contained a row of all 0s.
       (`#1123 <https://github.com/natcap/invest/issues/1123>`_)
+* Urban Nature Access
+    * Fixed an issue where, under certain circumstances, the model would raise
+      a cryptic ``TypeError`` when creating the summary vector.
+      https://github.com/natcap/invest/issues/1350
 * Visitation: Recreation and Tourism
     * Fixed a bug where overlapping predictor polygons would be double-counted
       in ``polygon_area_coverage`` and ``polygon_percent_coverage`` calculations.
diff --git a/src/natcap/invest/urban_nature_access.py b/src/natcap/invest/urban_nature_access.py
index 48b4ae703..113a1e5b3 100644
--- a/src/natcap/invest/urban_nature_access.py
+++ b/src/natcap/invest/urban_nature_access.py
@@ -2014,7 +2014,10 @@ def _write_supply_demand_vector(source_aoi_vector_path, feature_attrs,
     for feature in target_layer:
         feature_id = feature.GetFID()
         for attr_name, attr_value in feature_attrs[feature_id].items():
-            feature.SetField(attr_name, attr_value)
+            # It is possible that attr_value may be a numpy.float32 object,
+            # which will raise a cryptic error.  Numpy.float64 will not raise
+            # this error.  Casting to float avoids the issue.
+            feature.SetField(attr_name, float(attr_value))
 
         target_layer.SetFeature(feature)
     target_layer.CommitTransaction()