diff --git a/lib/rspec_api_documentation/client_base.rb b/lib/rspec_api_documentation/client_base.rb
index db0560a3..fc2793c0 100644
--- a/lib/rspec_api_documentation/client_base.rb
+++ b/lib/rspec_api_documentation/client_base.rb
@@ -44,7 +44,7 @@ def process(method, path, params = {}, headers ={})
     end
 
     def read_request_body
-      input = last_request.env["rack.input"]
+      input = last_request.env["rack.input"] || StringIO.new
       input.rewind
       input.read
     end