diff --git a/Cargo.toml b/Cargo.toml
index 4411058..872e0bf 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,7 +9,7 @@ links = "pq"
 build = "build.rs"
 
 [dependencies]
-openssl-sys = { version = "*", optional = true }
+openssl-sys = { version = ">= 0.9.0, < 0.11", optional = true }
 
 [features]
 openssl-static = ["openssl-sys"]