diff --git a/src/_bcrypt/Cargo.toml b/src/_bcrypt/Cargo.toml
index 5c810db9..8f450d96 100644
--- a/src/_bcrypt/Cargo.toml
+++ b/src/_bcrypt/Cargo.toml
@@ -3,6 +3,8 @@ name = "bcrypt-rust"
 version = "0.1.0"
 authors = ["The bcrypt developers <cryptography-dev@python.org>"]
 edition = "2018"
+# This specifies the MSRV
+rust-version = "1.64.0"
 publish = false
 
 [dependencies]