diff --git a/INSTALL.md b/INSTALL.md
index f50ea1db76..4ac4690c0f 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -47,6 +47,8 @@ sudo apt update && sudo apt upgrade
 ```
 Note that these commands will likely take a long time to finish.
 
+*Note: If the repository you plan to build was created before 2020/XX/YY (e.g. modifications of pokeemerald that haven't updated) then follow the [legacy WSL1 instructions](docs/legacy_WSL1_INSTALL.md). These repositories can be identified by the [older revision](https://github.com/pret/pokeemerald/blob/571c598/INSTALL.md) of the INSTALL.md*
+
 Certain packages are required to build pokeemerald. Install these packages by running the following command:
 ```bash
 sudo apt install build-essential binutils-arm-none-eabi git libpng-dev
diff --git a/docs/legacy_WSL1_INSTALL.md b/docs/legacy_WSL1_INSTALL.md
new file mode 100644
index 0000000000..f9ed7b0e21
--- /dev/null
+++ b/docs/legacy_WSL1_INSTALL.md
@@ -0,0 +1,32 @@
+### Setting up WSL1 (Legacy Portion)
+Certain packages are required to build pokeemerald. Install these packages by running the following command:
+```bash
+sudo apt install build-essential git libpng-dev gdebi-core
+```
+(If the above command does not work, try the above command but replacing `apt` with `apt-get`).
+
+Download the devkitPro software package [here](https://github.com/devkitPro/pacman/releases). The file to download is `devkitpro-pacman.amd64.deb`.
+
+WSL has its own file system that's not accessible from Windows, but Windows files *are* accessible from WSL. To install the devkitPro package, you'll need to change to the **current working directory** where the package file was saved.
+
+For example, if the package file was saved to **C:\Users\\_\<user>_\Downloads** (the Downloads location for most users), enter this command:
+
+```bash
+cd /mnt/c/Users/<user>/Downloads
+```
+
+(The Windows C:\ drive is called /mnt/c/ in WSL. Replace <user> in the example path with your **Windows** username. Windows path names are case-insensitive so adhereing to capitalization isn't needed)
+
+Once the directory has been changed to the folder containing the devkitPro package, run the following commands to install devkitPro.
+```bash
+sudo gdebi devkitpro-pacman.amd64.deb
+sudo dkp-pacman -Sy
+sudo dkp-pacman -S gba-dev
+```
+Note: the last command will ask for the selection of packages to install. Just press Enter to install all of them, followed by entering Y to proceed with the installation. `devkitpro-pacman.amd64.deb` is the expected filename of the devkitPro package downloaded (for the first command). If the downloaded package filename differs, then use that filename instead.
+
+Run the following command to set devkitPro related environment variables (alternatively, close and re-open WSL):
+```bash
+source /etc/profile.d/devkit-env.sh
+```
+Proceed to [Choosing where to store pokeemerald (WSL1) of the current INSTALL.md](/INSTALL.md#choosing-where-to-store-pokeemerald-(WSL1)).