diff --git a/src/control-flow-basics/exercise.md b/src/control-flow-basics/exercise.md
index 064a20f710f..6f7df66ddd5 100644
--- a/src/control-flow-basics/exercise.md
+++ b/src/control-flow-basics/exercise.md
@@ -1,5 +1,5 @@
 ---
-minutes: 30
+minutes: 15
 ---
 
 # Exercise: Collatz Sequence