diff --git a/wasm/Cargo.toml b/wasm/Cargo.toml
index f49ca5d..a65f294 100644
--- a/wasm/Cargo.toml
+++ b/wasm/Cargo.toml
@@ -2,6 +2,7 @@
 name = "utfdump_wasm"
 version = "0.1.0"
 edition = "2021"
+rust-version = "1.70.0"
 
 [lib]
 crate-type = ["cdylib", "rlib"]