diff --git a/Cargo.toml b/Cargo.toml
index 9419c71c69f..8d3b2b0188e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,7 +21,7 @@ indoc = { version = "0.3.6", optional = true }
 inventory = { version = "0.1.4", optional = true }
 libc = "0.2.62"
 parking_lot = "0.11.0"
-num-bigint = { version = "0.3", optional = true }
+num-bigint = { version = "0.4", optional = true }
 num-complex = { version = "0.3", optional = true }
 # must stay at 0.1.x for Rust 1.41 compatibility
 paste = { version = "0.1.18", optional = true }