diff --git a/Cargo.toml b/Cargo.toml
index 639b411c..fa809d98 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -47,6 +47,8 @@ version = "0.2.3"
 
 [dependencies.rustls]
 optional = true
+default-features = false
+features = ["std"]
 version = "0.23.0"
 
 [dependencies.rustls-pki-types]