diff --git a/spec/models/case_log_spec.rb b/spec/models/case_log_spec.rb
index f76bb8da8..d784c2fda 100644
--- a/spec/models/case_log_spec.rb
+++ b/spec/models/case_log_spec.rb
@@ -531,6 +531,29 @@ RSpec.describe CaseLog do
         expect(case_log["referral"]).to eq("Internal transfer")
       end
     end
+
+    context "when it is not a renewal" do
+      let!(:case_log) do
+        described_class.create({
+          managing_organisation: organisation,
+          owning_organisation: organisation,
+          renewal: "No",
+          year: 2021,
+        })
+      end
+
+      it "correctly derives and saves reasonpref when changed to renewal" do
+        case_log.update!({ reasonpref: "Yes" })
+        record_from_db = ActiveRecord::Base.connection.execute("select reasonpref from case_logs where id=#{case_log.id}").to_a[0]
+        expect(record_from_db["reasonpref"]).to eq(1)
+        expect(case_log["reasonpref"]).to eq("Yes")
+
+        case_log.update!({ renewal: "Yes" })
+        record_from_db = ActiveRecord::Base.connection.execute("select reasonpref from case_logs where id=#{case_log.id}").to_a[0]
+        expect(record_from_db["reasonpref"]).to eq(nil)
+        expect(case_log["reasonpref"]).to eq(nil)
+      end
+    end
   end
 
   describe "resetting invalidated fields" do