diff --git a/Cargo.lock b/Cargo.lock
index 152c1d307b..91a57bf796 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1082,9 +1082,7 @@ dependencies = [
  "difference",
  "ra_proc_macro",
  "ra_tt",
- "serde",
  "serde_derive",
- "serde_json",
 ]
 
 [[package]]
@@ -1414,18 +1412,18 @@ checksum = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 
 [[package]]
 name = "serde"
-version = "1.0.106"
+version = "1.0.104"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "36df6ac6412072f67cf767ebbde4133a5b2e88e76dc6187fa7104cd16f783399"
+checksum = "414115f25f818d7dfccec8ee535d76949ae78584fc4f79a6f45a904bf8ab4449"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.106"
+version = "1.0.104"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e549e3abf4fb8621bd1609f11dfc9f5e50320802273b12f3811a67e6716ea6c"
+checksum = "128f9e303a5a29922045a830221b8f78ec74a5f544944f3d5984f8ec3895ef64"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/crates/ra_proc_macro_srv/Cargo.toml b/crates/ra_proc_macro_srv/Cargo.toml
index 315191cc56..6300d668ab 100644
--- a/crates/ra_proc_macro_srv/Cargo.toml
+++ b/crates/ra_proc_macro_srv/Cargo.toml
@@ -12,10 +12,9 @@ doctest = false
 ra_tt = { path = "../ra_tt" }
 ra_proc_macro = { path = "../ra_proc_macro" }
 
-serde_derive = "1.0.104"
-serde = "1.0.104"
-serde_json = "1.0.48"
 
 [dev-dependencies]
 cargo_metadata = "0.9.1"
 difference = "2.0.0"
+# used as proc macro test target
+serde_derive = "=1.0.104"
\ No newline at end of file