diff --git a/SDL3/SDL_BUTTON.md b/SDL3/SDL_BUTTON.md
index 4555050ab..a43e1c201 100644
--- a/SDL3/SDL_BUTTON.md
+++ b/SDL3/SDL_BUTTON.md
@@ -18,6 +18,8 @@ Defined in [SDL_mouse.h](https://github.com/libsdl-org/SDL/blob/main/include/SDL
 - Button 1: Left mouse button
 - Button 2: Middle mouse button
 - Button 3: Right mouse button
+- Button 4: Side mouse button 1
+- Button 5: Side mouse button 2
 
 ## Version