diff --git a/src/exercises/day-4/morning.md b/src/exercises/day-4/morning.md
index c289ded0..e9b65a01 100644
--- a/src/exercises/day-4/morning.md
+++ b/src/exercises/day-4/morning.md
@@ -2,7 +2,7 @@
 
 Let us practice our new concurrency skills with
 
-* Dining philosophers: a classic problems in concurrency.
+* Dining philosophers: a classic problem in concurrency.
 
 * Multi-threaded link checker: a larger project where you'll use Cargo to
   download dependencies and then check links in parallel.