diff --git a/lean-toolchain b/lean-toolchain
index 987da87368..d5b1c84235 100644
--- a/lean-toolchain
+++ b/lean-toolchain
@@ -1 +1 @@
-leanprover/lean4:nightly-2021-12-13
+leanprover/lean4:nightly-2021-12-15