diff --git a/src/doc/rustc-dev-guide/src/traits/regions.md b/src/doc/rustc-dev-guide/src/traits/regions.md
index baa3582b639b..4657529dc2bd 100644
--- a/src/doc/rustc-dev-guide/src/traits/regions.md
+++ b/src/doc/rustc-dev-guide/src/traits/regions.md
@@ -1,3 +1,9 @@
 # Region constraints
 
-*to be written*
+*To be written.*
+
+Chalk does not have the concept of region constraints, and as of this
+writing, work on rustc was not far enough to worry about them.
+
+In the meantime, you can read about region constraints in the
+[type inference](../type-inference.html#region-constraints) section.