diff --git a/Cargo.toml b/Cargo.toml
index 339f8f5edd7837d35b1115453a8590aac363d184..0111c5509eb738484982e085a3da446386f226d0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,8 +14,8 @@ internet=["libc"]
 
 [dependencies]
 
-# ffi
-libc = { version = "^0.2", optional = true }
+libc = { version = "^0.2", optional = true } # raw sockets
+mio = { version = "0.8", features = ["os-poll"] } # cross-platform IO notification queue
 
 # randomness
 rand = "0.8.4"