diff --git a/foundationdb-bindingtester/Cargo.toml b/foundationdb-bindingtester/Cargo.toml
index 2144faa2..d5dc8f2c 100644
--- a/foundationdb-bindingtester/Cargo.toml
+++ b/foundationdb-bindingtester/Cargo.toml
@@ -35,5 +35,5 @@ foundationdb = { path = "../foundationdb", features = ["uuid", "num-bigint"], de
 foundationdb-sys = { version = "0.5.1", path = "../foundationdb-sys", default-features = false }
 futures = "0.3.0"
 log = "0.4.8"
-num-bigint = "0.3.0"
+num-bigint = "0.4.0"
 structopt = "0.3.3"
diff --git a/foundationdb/Cargo.toml b/foundationdb/Cargo.toml
index a244ca0c..2d391a3e 100644
--- a/foundationdb/Cargo.toml
+++ b/foundationdb/Cargo.toml
@@ -48,7 +48,7 @@ memchr = "2.2.1"
 rand = { version = "0.7.2", features = ["default", "small_rng"] }
 static_assertions = "1.1.0"
 uuid = { version = "0.8.1", optional = true }
-num-bigint = { version = "0.3.0", optional = true }
+num-bigint = { version = "0.4.0", optional = true }
 
 [dev-dependencies]
 byteorder = "1.3.2"