diff --git a/crates/backend/Cargo.toml b/crates/backend/Cargo.toml
index 263256fba..dae14fcb5 100644
--- a/crates/backend/Cargo.toml
+++ b/crates/backend/Cargo.toml
@@ -11,7 +11,7 @@ Backend code generation of the wasm-bindgen tool
 """
 
 [features]
-spans = []
+spans = ["proc-macro2/nightly"]
 
 [dependencies]
 quote = '0.6'
diff --git a/crates/macro/Cargo.toml b/crates/macro/Cargo.toml
index 92a6a18ca..cb75fd755 100644
--- a/crates/macro/Cargo.toml
+++ b/crates/macro/Cargo.toml
@@ -14,7 +14,7 @@ Definition of the `#[wasm_bindgen]` attribute, an internal dependency
 proc-macro = true
 
 [features]
-spans = ["wasm-bindgen-backend/spans"]
+spans = ["proc-macro2/nightly", "wasm-bindgen-backend/spans"]
 
 [dependencies]
 syn = { version = '0.14', features = ['full'] }