diff --git a/docs/guides/BUILDING.md b/docs/guides/BUILDING.md
index 78ad0ecd0d6e0a..08900d3313e340 100644
--- a/docs/guides/BUILDING.md
+++ b/docs/guides/BUILDING.md
@@ -55,10 +55,26 @@ sudo apt-get install git gcc g++ pkg-config libssl-dev libdbus-1-dev \
      python3-pip unzip libgirepository1.0-dev libcairo2-dev libreadline-dev
 ```
 
+#### UI builds
+
+If building `-with-ui` variant, also install SDL2:
+
+```
+sudo apt-get install libsdl2-dev
+```
+
 ### Installing prerequisites on macOS
 
 On macOS, install Xcode from the Mac App Store.
 
+#### UI builds
+
+If building `-with-ui` variant, also install SDL2:
+
+```
+brew install sdl2
+```
+
 ### Installing prerequisites on Raspberry Pi 4
 
 Complete the following steps: