diff --git a/examples/guide-supported-types-examples/Cargo.toml b/examples/guide-supported-types-examples/Cargo.toml
index a98c80f4..3e1d046a 100644
--- a/examples/guide-supported-types-examples/Cargo.toml
+++ b/examples/guide-supported-types-examples/Cargo.toml
@@ -2,6 +2,7 @@
 name = "guide-supported-types-examples"
 version = "0.1.0"
 authors = ["The wasm-bindgen Developers"]
+edition = "2018"
 
 [lib]
 crate-type = ["cdylib"]