diff --git a/rustls/Cargo.toml b/rustls/Cargo.toml
index c75c035a..dbde3f6a 100644
--- a/rustls/Cargo.toml
+++ b/rustls/Cargo.toml
@@ -12,7 +12,7 @@ categories = ["network-programming", "cryptography"]
 autobenches = false
 
 [dependencies]
-base64 = "0.12"
+base64 = "=0.12.1"
 log = { version = "0.4.4", optional = true }
 ring = "0.16.11"
 sct = "0.6.0"