diff --git a/mplex/Cargo.toml b/mplex/Cargo.toml
index 995d4df3..0af55d9c 100644
--- a/mplex/Cargo.toml
+++ b/mplex/Cargo.toml
@@ -6,7 +6,7 @@ authors = ["Parity Technologies <admin@parity.io>"]
 [dependencies]
 bytes = "0.4.5"
 num-traits = "0.1.40"
-num-bigint = "0.1.40"
+num-bigint = { version = "0.1.40", default-features = false }
 tokio-io = "0.1"
 futures = "0.1"
 parking_lot = "0.4.8"
diff --git a/varint-rs/Cargo.toml b/varint-rs/Cargo.toml
index fb2fca18..8e282760 100644
--- a/varint-rs/Cargo.toml
+++ b/varint-rs/Cargo.toml
@@ -4,7 +4,7 @@ version = "0.1.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 
 [dependencies]
-num-bigint = "0.1.40"
+num-bigint = { version = "0.1.40", default-features = false }
 num-traits = "0.1.40"
 bytes = "0.4.5"
 tokio-io = "0.1"