--- a/Cargo.toml
+++ b/Cargo.toml
@@ -42,9 +42,9 @@
 version = "3.1.0"
 
 [dependencies.which]
-version = "4.0"
+version = ">= 4.0"
 optional = true
-default-features = false
+features = ["real-sys"]
 
 [features]
 better-path = ["which"]