diff --git a/spec/Cargo.lock b/spec/Cargo.lock
index 1258509..f4deb5c 100644
--- a/spec/Cargo.lock
+++ b/spec/Cargo.lock
@@ -2,20 +2,11 @@
 # It is not intended for manual editing.
 version = 3
 
-[[package]]
-name = "basic-toml"
-version = "0.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7bfc506e7a2370ec239e1d072507b2a80c833083699d3c6fa176fbb4de8448c6"
-dependencies = [
- "serde",
-]
-
 [[package]]
 name = "darling"
-version = "0.20.3"
+version = "0.20.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0209d94da627ab5605dcccf08bb18afa5009cfbef48d8a8b7d7bdbc79be25c5e"
+checksum = "da01daa5f6d41c91358398e8db4dde38e292378da1f28300b59ef4732b879454"
 dependencies = [
  "darling_core",
  "darling_macro",
@@ -23,9 +14,9 @@ dependencies = [
 
 [[package]]
 name = "darling_core"
-version = "0.20.3"
+version = "0.20.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "177e3443818124b357d8e76f53be906d60937f0d3a90773a664fa63fa253e621"
+checksum = "f44f6238b948a3c6c3073cdf53bb0c2d5e024ee27e0f35bfe9d556a12395808a"
 dependencies = [
  "fnv",
  "ident_case",
@@ -37,51 +28,27 @@ dependencies = [
 
 [[package]]
 name = "darling_macro"
-version = "0.20.3"
+version = "0.20.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "836a9bbc7ad63342d6d6e7b815ccab164bc77a2d95d84bc3117a8c0d5c98e2d5"
+checksum = "0d2d88bd93979b1feb760a6b5c531ac5ba06bd63e74894c377af02faee07b9cd"
 dependencies = [
  "darling_core",
  "quote",
  "syn",
 ]
 
-[[package]]
-name = "dissimilar"
-version = "1.0.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "86e3bdc80eee6e16b2b6b0f87fbc98c04bee3455e35174c0de1a125d0688c632"
-
 [[package]]
 name = "fnv"
 version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
-[[package]]
-name = "glob"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d2fabcfbdc87f4758337ca535fb41a6d701b65693ce38287d856d1674551ec9b"
-
 [[package]]
 name = "ident_case"
 version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
 
-[[package]]
-name = "itoa"
-version = "1.0.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "af150ab688ff2122fcef229be89cb50dd66af9e01a4ff320cc137eecc9bacc38"
-
-[[package]]
-name = "once_cell"
-version = "1.18.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dd8b5dd2ae5ed71462c540258bedcb51965123ad7e7ccf4b9a8cafaa4a63576d"
-
 [[package]]
 name = "proc-macro2"
 version = "1.0.66"
@@ -100,51 +67,11 @@ dependencies = [
  "proc-macro2",
 ]
 
-[[package]]
-name = "ryu"
-version = "1.0.15"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ad4cc8da4ef723ed60bced201181d83791ad433213d8c24efffda1eec85d741"
-
-[[package]]
-name = "serde"
-version = "1.0.188"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cf9e0fcba69a370eed61bcf2b728575f726b50b55cba78064753d708ddc7549e"
-dependencies = [
- "serde_derive",
-]
-
-[[package]]
-name = "serde_derive"
-version = "1.0.188"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4eca7ac642d82aa35b60049a6eccb4be6be75e599bd2e9adb5f875a737654af2"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
-[[package]]
-name = "serde_json"
-version = "1.0.105"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "693151e1ac27563d6dbcec9dee9fbd5da8539b20fa14ad3752b2e6d363ace360"
-dependencies = [
- "itoa",
- "ryu",
- "serde",
-]
-
 [[package]]
 name = "spec"
 version = "0.1.0"
 dependencies = [
  "darling",
- "proc-macro2",
- "syn",
- "trybuild",
 ]
 
 [[package]]
@@ -164,64 +91,8 @@ dependencies = [
  "unicode-ident",
 ]
 
-[[package]]
-name = "termcolor"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "be55cf8942feac5c765c2c993422806843c9a9a45d4d5c407ad6dd2ea95eb9b6"
-dependencies = [
- "winapi-util",
-]
-
-[[package]]
-name = "trybuild"
-version = "1.0.83"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6df60d81823ed9c520ee897489573da4b1d79ffbe006b8134f46de1a1aa03555"
-dependencies = [
- "basic-toml",
- "dissimilar",
- "glob",
- "once_cell",
- "serde",
- "serde_derive",
- "serde_json",
- "termcolor",
-]
-
 [[package]]
 name = "unicode-ident"
 version = "1.0.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "301abaae475aa91687eb82514b328ab47a211a533026cb25fc3e519b86adfc3c"
-
-[[package]]
-name = "winapi"
-version = "0.3.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
-dependencies = [
- "winapi-i686-pc-windows-gnu",
- "winapi-x86_64-pc-windows-gnu",
-]
-
-[[package]]
-name = "winapi-i686-pc-windows-gnu"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
-
-[[package]]
-name = "winapi-util"
-version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "70ec6ce85bb158151cae5e5c87f95a8e97d2c0c4b001223f33a334e3ce5de178"
-dependencies = [
- "winapi",
-]
-
-[[package]]
-name = "winapi-x86_64-pc-windows-gnu"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/spec/Cargo.toml b/spec/Cargo.toml
index 5925c64..29e690d 100644
--- a/spec/Cargo.toml
+++ b/spec/Cargo.toml
@@ -9,5 +9,5 @@ path = "src/lib.rs"
 proc-macro = true
 
 [dependencies]
-darling = "0.20.3"
+darling = "0.20.4"