diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index 69ca050d0c..b10f6b48c7 100644
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -157,7 +157,8 @@ module ActionDispatch
 
     # Originating IP address, usually set by the RemoteIp middleware.
     def remote_ip
-      @remote_ip ||= (@env["action_dispatch.remote_ip"] || ip).to_s
+      # Coerce the remote_ip object into a string, because to_s could return nil
+      @remote_ip ||= @env["action_dispatch.remote_ip"].to_s || ip
     end
 
     # Returns the unique request id, which is based off either the X-Request-Id header that can