diff --git a/simulation/readme.md b/simulation/readme.md
index ec60418..a07c2cc 100644
--- a/simulation/readme.md
+++ b/simulation/readme.md
@@ -2,12 +2,15 @@
 
 This is a simple SDL2 based simulator that runs the NuEVI firmware compiled for MacOS. This is for testing the menu and is not supposed to produce any midi events.
 
+
 ### Requirements
 
  * The Filters library must be installed in ~/Documents/Arduino/libraries/Filters.
  * SDL2 must be installed on your machine.
  * You probably need to have XCode and XCodes command line tools installed as well.
 
+[Dear Imgui](https://github.com/ocornut/imgui) is pulled in as an git submodule. Run `git submoudule init` and `git submodule update` to get the code. The code is tested with tag v1.70 of ImGui, so if you run into problems make sure that is the checked out version.
+
 
 ### Know limitations