diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 622e389..b0a77c4 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -24,7 +24,7 @@
 
 ## External dependencies
 # Intended to match Fuchsia versions.
-aes = "0.9.1"
+aes = "=0.9.1"
 assert_matches = "1.5.0"
 bitfield = "0.19.4"
 bitflags = "2.11.1"