diff --git a/Cargo.lock b/Cargo.lock
index 92169d96..d1739237 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -580,11 +580,12 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.120"
+version = "1.0.140"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e0d21c9a8cae1235ad58a00c11cb40d4b1e5c784f1ef2c537876ed6ffd8b7c5"
+checksum = "20068b6e96dc6c9bd23e01df8827e6c7e1f2fddd43c21810382803c136b99373"
 dependencies = [
  "itoa",
+ "memchr",
  "ryu",
  "serde",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 5f62df0a..3832c37a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,7 +24,7 @@ thiserror = "1.0"
 libc = "0.2.155"
 streaming-iterator = "0.1.5"
 serde = {version = "1.0.203", features = ["derive"], optional = true}
-serde_json = {version = "1.0.120", optional = true}
+serde_json = {version = "1.0.140", optional = true}
 bincode = {version = "1.3.1", optional = true}
 tskit-derive = {version = "0.2.0", path = "tskit-derive", optional = true}
 chrono = { version = "0.4.40", default-features = false, features = ["now", "std"] , optional = true}
@@ -34,7 +34,7 @@ anyhow = {version = "1.0.86"}
 clap = {version = "4.4.6", features = ["derive"]}
 serde = {version = "1.0.203", features = ["derive"]}
 serde-pickle = "1.1.0"
-serde_json = {version = "1.0.120"}
+serde_json = {version = "1.0.140"}
 bincode = "1.3.1"
 rand = "0.8.3"
 rand_distr = "0.4.0"