diff --git a/README.md b/README.md
index cb28ffe..f2220de 100644
--- a/README.md
+++ b/README.md
@@ -184,6 +184,8 @@ All global identifiers of the game code start with the prefix `SFG_` (meaning *s
 
 The **engine** -- raycastlib -- works on the principle of **raycasting** on a square grid and handles the rendering of the 3D environment (minus sprites). There is a copy of raycastlib in this repository but I maintain raycastlib as a separate project in a different repository, which you can see for more details about it. For us, the important functions interfacing with the engine are e.g. `SFG_floorHeightAt`, `SFG_ceilingHeightAt` (functions the engine uses to retirieve floor and ceiling height) and `SFG_pixelFunc` (function the engine uses to write pixels to the screen during rendering, which in turn uses each platform's specific `SFG_setPixel`).
 
+**Mods** of the vanilla version are recommended to be made as patches, so that they can easily be combined etc. If you want your mod to remain free, please don't forget a license/waiver, even for a small mod. You can never go wrong by including it.
+
 integer math
 
 sprites 1D zbuffer