diff --git a/docs/src/extensions.md b/docs/src/extensions.md
index 7aaf9db14..281d8ef2e 100644
--- a/docs/src/extensions.md
+++ b/docs/src/extensions.md
@@ -5,6 +5,21 @@ features that are not supported by GNU coreutils. We take care not to introduce
 features that are incompatible with the GNU coreutils. Below is a list of uutils
 extensions.
 
+## General
+
+GNU coreutils provides two ways to define short options taking an argument:
+
+```
+$ ls -w 80
+$ ls -w80
+```
+
+We support a third way:
+
+```
+$ ls -w=80
+```
+
 ## `env`
 
 `env` has an additional `-f`/`--file` flag that can parse `.env` files and set