diff --git a/Cargo.toml b/Cargo.toml
index e699a7e..6392477 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,4 +21,4 @@ alloc = ["hashbrown"]
 
 [dev-dependencies]
 # Keep the MSRV test graph compatible with Rust 1.61.
-once_cell = "=1.19.0"
+once_cell = "=1.21.4"