diff --git a/Cargo.lock b/Cargo.lock
index 7887bc2176..f9265af438 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1079,7 +1079,6 @@ dependencies = [
  "log",
  "ra_tt",
  "serde",
- "serde_derive",
  "serde_json",
 ]
 
diff --git a/crates/ra_proc_macro/Cargo.toml b/crates/ra_proc_macro/Cargo.toml
index 7b4ff993f3..f4a1b6d9e9 100644
--- a/crates/ra_proc_macro/Cargo.toml
+++ b/crates/ra_proc_macro/Cargo.toml
@@ -10,8 +10,7 @@ doctest = false
 
 [dependencies]
 ra_tt = { path = "../ra_tt" }
-serde_derive = "1.0.104"
-serde = "1.0.104"
-serde_json = "1.0.48"
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
 log = "0.4.8"
 crossbeam-channel = "0.4.0"
diff --git a/crates/ra_proc_macro/src/rpc.rs b/crates/ra_proc_macro/src/rpc.rs
index e7eaf7c15b..f88d91f782 100644
--- a/crates/ra_proc_macro/src/rpc.rs
+++ b/crates/ra_proc_macro/src/rpc.rs
@@ -252,7 +252,7 @@ mod tests {
         assert_eq!(task.macro_body, back.macro_body);
 
         let result = ExpansionResult { expansion: tt.clone() };
-        let json = serde_json::to_string(&task).unwrap();
+        let json = serde_json::to_string(&result).unwrap();
         let back: ExpansionResult = serde_json::from_str(&json).unwrap();
 
         assert_eq!(result, back);