diff --git a/BUILDING.md b/BUILDING.md
index 75f480b0b9..9e2405c593 100644
--- a/BUILDING.md
+++ b/BUILDING.md
@@ -43,7 +43,7 @@ Now just run `OpenSim.exe` from the `bin` folder, and set up the region.
  * libgdiplus 
  
  if you have mono 6.x complete, you already have libgdiplus, otherwise you need to install it
- using a package manager for your operating system, like atp, brew, macports, etc
+ using a package manager for your operating system, like apt, brew, macports, etc
  for example on debian:
  
  `apt-get update && apt-get install -y apt-utils libgdiplus libc6-dev`