diff --git a/openssl-sys/Cargo.toml b/openssl-sys/Cargo.toml
index 92c4dc0d..8b7203ab 100644
--- a/openssl-sys/Cargo.toml
+++ b/openssl-sys/Cargo.toml
@@ -18,4 +18,4 @@ sslv2 = []
 aes_xts = []
 
 [build-dependencies]
-pkg-config = "*"
+pkg-config = "0.1"