diff --git a/src/borrow_check/region_inference/constraint_propagation.md b/src/borrow_check/region_inference/constraint_propagation.md
index e2c36062..385e0489 100644
--- a/src/borrow_check/region_inference/constraint_propagation.md
+++ b/src/borrow_check/region_inference/constraint_propagation.md
@@ -178,7 +178,7 @@ easily just by taking the union:
 
 ```
 for each region R:
-  let S by the SCC that contains R
+  let S be the SCC that contains R
   Values(S) = Values(S) union Liveness(R)
 ```