Aspects include applying a patch to a first instance of software code and verifying that the first instance of the software code with the patch applied is operating as expected. The verifying includes sending a request to the first instance of the software code and sending the request to a second instance of the software code where the patch was previously applied. The verifying also includes comparing a first result received from the first instance of the software code in response to the request and a second result received from the second instance of the software code in response to the request. The verifying further includes determining that the first instance of the software code with the patch applied is operating as expected based on the first result being within a similarity threshold of the second result.