diff --git a/test/providers/omniva_provider_test.rb b/test/providers/omniva_provider_test.rb
index 9799849..8e50d21 100644
--- a/test/providers/omniva_provider_test.rb
+++ b/test/providers/omniva_provider_test.rb
@@ -22,7 +22,7 @@ def test_sends_normalized_e_invoice
                    .to_return(status: 200, body: response_body)
 
     main_request = stub_request(:post, 'https://provider.test/endpoint')
-                   .with(body: main_request_body)
+                   .with(body: main_request_body_pattern)
                    .to_return(status: 200, body: '')
 
     provider = EInvoice::Providers::OmnivaProvider.new(wsdl_production: 'https://provider.test/wsdl.xml',
@@ -49,7 +49,7 @@ def test_uses_production_wsdl_when_test_mode_is_off
 
   private
 
-  def main_request_body
-    '<?xml version="1.0" encoding="UTF-8"?><env:Envelope xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tns="http://e-arvetekeskus.eu/erp" xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:sch1="http://www.pangaliit.ee/arveldused/e-arve/" xmlns:sch0="http://e-arvetekeskus.eu/erp" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"><env:Body><tns:EInvoiceRequest authPhrase="test-password"><E_Invoice/></tns:EInvoiceRequest></env:Body></env:Envelope>'
+  def main_request_body_pattern
+    %r{<env:Body><tns:EInvoiceRequest authPhrase="test-password"><E_Invoice/></tns:EInvoiceRequest></env:Body>}
   end
 end
\ No newline at end of file