diff --git a/lib/active_merchant/billing/gateways/flex_charge.rb b/lib/active_merchant/billing/gateways/flex_charge.rb
index ed2ab26e96d..3471711e72a 100644
--- a/lib/active_merchant/billing/gateways/flex_charge.rb
+++ b/lib/active_merchant/billing/gateways/flex_charge.rb
@@ -30,9 +30,8 @@ def initialize(options = {})
       end
 
       def purchase(money, credit_card, options = {})
-        options[:transactionType] ||= 'Purchase'
+        post = { transactionType: options.fetch(:transactionType, 'Purchase') }
 
-        post = {}
         add_merchant_data(post, options)
         add_base_data(post, options)
         add_invoice(post, money, credit_card, options)
@@ -198,7 +197,6 @@ def add_invoice(post, money, credit_card, options)
           avsResultCode: options[:avs_result_code],
           cvvResultCode: options[:cvv_result_code],
           cavvResultCode: options[:cavv_result_code],
-          transactionType: options[:transactionType],
           cardNotPresent: credit_card.is_a?(String) ? false : credit_card.verification_value.blank?
         }.compact
       end
diff --git a/test/remote/gateways/remote_flex_charge_test.rb b/test/remote/gateways/remote_flex_charge_test.rb
index 1c1d5c2125f..d38cff1a7b6 100644
--- a/test/remote/gateways/remote_flex_charge_test.rb
+++ b/test/remote/gateways/remote_flex_charge_test.rb
@@ -27,7 +27,7 @@ def setup
       cavv_result_code: '111',
       timezone_utc_offset: '-5',
       billing_address: address.merge(name: 'Cure Tester'),
-      extra_data: { hello: 'world' }.to_json
+      extra_data: ''
     }
 
     @cit_options = @options.merge(
diff --git a/test/unit/gateways/flex_charge_test.rb b/test/unit/gateways/flex_charge_test.rb
index 2c6eabc1a91..09683bc59f3 100644
--- a/test/unit/gateways/flex_charge_test.rb
+++ b/test/unit/gateways/flex_charge_test.rb
@@ -119,7 +119,7 @@ def test_successful_purchase
         assert_equal request['transaction']['avsResultCode'], @options[:avs_result_code]
         assert_equal request['transaction']['cvvResultCode'], @options[:cvv_result_code]
         assert_equal request['transaction']['cavvResultCode'], @options[:cavv_result_code]
-        assert_equal request['transaction']['transactionType'], 'Purchase'
+        assert_equal request['transactionType'], 'Purchase'
         assert_equal request['payer']['email'], @options[:email]
         assert_equal request['description'], @options[:description]
 
@@ -141,7 +141,7 @@ def test_successful_authorization
       @gateway.authorize(@amount, @credit_card, @options)
     end.check_request do |_method, endpoint, data, _headers|
       request = JSON.parse(data)
-      assert_equal request['transaction']['transactionType'], 'Authorization' if /evaluate/.match?(endpoint)
+      assert_equal request['transactionType'], 'Authorization' if /evaluate/.match?(endpoint)
     end.respond_with(successful_access_token_response, successful_purchase_response)
   end