diff --git a/doc/src/core-transmutation.md b/doc/src/core-transmutation.md
index ba66c41be7e18..3a71c0c12ff29 100644
--- a/doc/src/core-transmutation.md
+++ b/doc/src/core-transmutation.md
@@ -1,4 +1,4 @@
-# Challenge: Verify `core` transmuting methods
+# Challenge 1: Verify `core` transmuting methods
 
 - **Status:** Open
 - **Tracking Issue:** [Link to issue](https://github.com/model-checking/verify-rust-std/issues/19)