diff --git a/README.md b/README.md
index 59c8154..237917d 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ LIBRARY_PATH=/opt/homebrew/lib jam -lSDL2 -C opt-level=3 -o jamstation main.jam
 ./jamstation /path/to/SCPH1001.BIN
 ```
 
-- **`BIOS_PATH`** - the PSX BIOS image.
+- **`BIOS_PATH`** - the PSX BIOS image. The original Sony BIOS (e.g. `SCPH1001.BIN`) is copyrighted; if you don't own one, the [PCSX-Redux OpenBIOS](https://github.com/grumpycoders/pcsx-redux) is a free, open-source replacement that boots most software.
 - **`GAME_PATH`** - optional, dispatched by extension:
   - `.cue` / `.bin` (disc image); the BIOS bootstraps it off the disc. Pass the **`.cue`**, not the game folder, its `.bin` tracks are resolved relative to the cue (multi-track and spaces in the name are fine, so quote paths with spaces).
   - `.exe` - a PS-X executable, sideloaded after the BIOS boots.