diff --git a/Cargo.lock b/Cargo.lock
index 8da89728..de5415c2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -41,7 +41,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 1.0.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -527,7 +527,7 @@ dependencies = [
  "proc-macro-hack 0.5.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 1.0.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1079,7 +1079,7 @@ dependencies = [
  "pg-extend 0.2.1",
  "proc-macro2 1.0.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1113,7 +1113,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 1.0.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1358,7 +1358,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 1.0.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1473,7 +1473,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "syn"
-version = "1.0.39"
+version = "1.0.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 1.0.19 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1897,7 +1897,7 @@ dependencies = [
 "checksum strip-ansi-escapes 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9d63676e2abafa709460982ddc02a3bb586b6d15a49b75c212e06edd3933acee"
 "checksum strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 "checksum subtle 2.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "502d53007c02d7605a05df1c1a73ee436952781653da5d0bf57ad608f66932c1"
-"checksum syn 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)" = "891d8d6567fe7c7f8835a3a98af4208f3846fba258c1bc3c31d6e506239f11f9"
+"checksum syn 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)" = "963f7d3cc59b59b9325165add223142bbf1df27655d07789f109896d353d8350"
 "checksum tar 0.4.29 (registry+https://github.com/rust-lang/crates.io-index)" = "c8a4c1d0bee3230179544336c15eefb563cf0302955d962e456542323e8c2e8a"
 "checksum tempfile 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e24d9338a0a5be79593e2fa15a648add6138caa803e2d5bc782c371732ca9"
 "checksum termcolor 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bb6bfa289a4d7c5766392812c0a1f4c1ba45afa1ad47803c11e1f407d846d75f"
diff --git a/pg-extern-attr/Cargo.toml b/pg-extern-attr/Cargo.toml
index 7af571bd..07d05b14 100644
--- a/pg-extern-attr/Cargo.toml
+++ b/pg-extern-attr/Cargo.toml
@@ -18,7 +18,7 @@ license = "MIT/Apache-2.0"
 proc-macro = true
 
 [dependencies]
-syn = { version = "1.0.33", features = ["extra-traits", "full", "fold", "parsing"] }
+syn = { version = "1.0.40", features = ["extra-traits", "full", "fold", "parsing"] }
 quote = "1.0.7"
 proc-macro2 = "1.0.17"