1 files changed, 5 insertions, 1 deletions

diff --git a/INSTALL.md b/INSTALL.md
index a2b9230..53264c2 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -9,9 +9,13 @@ installed like this:
 pip3 install mat2
 ```
 
-
 # GNU/Linux
 
+## Optional dependencies
+
+When [bubblewrap](https://github.com/projectatomic/bubblewrap) is
+installed, MAT2 uses it to sandbox any external processes it invokes.
+
 ## Fedora
 
 Thanks to [atenart](https://ack.tf/), there is a package available on