diff --git a/app/models/ona_transformation.rb b/app/models/ona_transformation.rb
index 6f9c5ca..371b199 100644
--- a/app/models/ona_transformation.rb
+++ b/app/models/ona_transformation.rb
@@ -63,13 +63,13 @@ def self.facility_categories(facility_data, categories, mappings)
 
             false_match = false
             false_values.each do |false_v|
-              false_match = false_match || mapping_value.include?(false_v)
+              false_match = false_match || (!mapping_value.nil? && mapping_value.include?(false_v))
             end
 
             if !false_match
               true_match = false
               true_values.each do |true_v|
-                true_match = true_match || mapping_value.include?(true_v)
+                true_match = true_match || (!mapping_value.nil? && mapping_value.include?(true_v))
               end
 
               if true_values.length == 0 || true_match
diff --git a/spec/ona_transformation_spec.rb b/spec/ona_transformation_spec.rb
index c35a8d6..7d21556 100644
--- a/spec/ona_transformation_spec.rb
+++ b/spec/ona_transformation_spec.rb
@@ -213,4 +213,23 @@ def mappings_data_sample
         ["1", "category_id_1"]
       ])
   end
+
+  it "allows data to be nil for a mapped field" do
+    facility_data = [
+      ["id", "fac_field_1", "fac_field_2", "fac_field_3"],
+      ["1", nil, "value_1_2", "value_1_3"]
+    ]
+
+    categories = categories_data_sample
+
+    mappings = [
+      MAPPINGS_HEADER,
+      ["category_id_1", "fac_field_1", "", "no result"]
+    ]
+    expect(OnaTransformation.facility_categories(facility_data, categories, mappings))
+      .to eq([
+        FACILITY_CATEGORIES_HEADER,
+        ["1", "category_id_1"]
+      ])
+  end
 end