diff --git a/Cargo.lock b/Cargo.lock
index a50d7d9bb..150fc8944 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -164,7 +164,7 @@ checksum = "16e62a023e7c117e27523144c5d2459f4397fcc3cab0085af8e2224f643a0193"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -175,7 +175,7 @@ checksum = "c6fa2087f2753a7da8cc1c0dbfcf89579dd57458e36769de5ac750b4671737ca"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -786,7 +786,7 @@ dependencies = [
  "heck",
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -1234,7 +1234,7 @@ checksum = "87750cf4b7a4c0625b1529e4c543c2182106e4dedc60a2a6455e00d212c489ac"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -1796,7 +1796,7 @@ version = "0.4.0"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -2162,7 +2162,7 @@ dependencies = [
  "pest_meta",
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -2203,7 +2203,7 @@ checksum = "2f38a4412a78282e09a2cf38d195ea5420d15ba0602cb375210efbc877243965"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -2257,7 +2257,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8d3928fb5db768cb86f891ff014f0144589297e3c6a1aba6ed7cecfdace270c7"
 dependencies = [
  "proc-macro2",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -2313,7 +2313,7 @@ checksum = "440f724eba9f6996b75d63681b0a92b06947f1457076d503a4d2e2c8f56442b8"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -2343,7 +2343,7 @@ dependencies = [
  "prost",
  "prost-types",
  "regex",
- "syn 2.0.52",
+ "syn 2.0.66",
  "tempfile",
 ]
 
@@ -2357,7 +2357,7 @@ dependencies = [
  "itertools",
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -2804,7 +2804,7 @@ checksum = "c5e405930b9796f1c00bee880d03fc7e0bb4b9a11afc776885ffe84320da2865"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -2874,7 +2874,7 @@ checksum = "82fe9db325bcef1fbcde82e078a5cc4efdf787e96b3b9cf45b50b529f2083d67"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -3020,9 +3020,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.52"
+version = "2.0.66"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b699d15b36d1f02c3e7c69f8ffef53de37aefae075d8488d4ba1a7788d574a07"
+checksum = "c42f3f41a2de00b01c0aaad383c5a45241efc8b2d1eda5661812fda5f3cdcff5"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -3064,7 +3064,7 @@ checksum = "e2470041c06ec3ac1ab38d0356a6119054dedaea53e12fbefc0de730a1c08524"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -3160,7 +3160,7 @@ checksum = "5b8a1e28f2deaa14e508979454cb3a223b10b938b45af148bc0986de36f1923b"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -3288,7 +3288,7 @@ dependencies = [
  "proc-macro2",
  "prost-build",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -3343,7 +3343,7 @@ checksum = "34704c8d6ebcbc939824180af020566b01a7c01f80641264eba0999f6c2b6be7"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
@@ -3715,7 +3715,7 @@ checksum = "15e934569e47891f7d9411f1a451d947a60e000ab3bd24fbb970f000387d1b3b"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.52",
+ "syn 2.0.66",
 ]
 
 [[package]]
diff --git a/nativelink-macro/Cargo.toml b/nativelink-macro/Cargo.toml
index 3fdbc24d9..3b0d8926e 100644
--- a/nativelink-macro/Cargo.toml
+++ b/nativelink-macro/Cargo.toml
@@ -11,4 +11,4 @@ crate_type = ["proc-macro"]
 # Some down-stream can't be upgraded just yet.
 proc-macro2 = "=1.0.84"
 quote = "=1.0.36"
-syn = "=2.0.52"
+syn = "=2.0.66"