diff --git a/Cargo.toml b/Cargo.toml
index 55ecca7..c29805a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,6 +14,6 @@ futures = "0.3"
 hotshot-types = { git = "https://github.com/EspressoSystems/hotshot-types", tag = "0.1.5" }
 serde = { version = "1.0", features = ["derive"] }
 snafu = { version = "0.7", features = ["backtraces"] }
-tagged-base64 = { git = "https://github.com/EspressoSystems/tagged-base64", tag = "0.3.4" }
+tagged-base64 = { git = "https://github.com/EspressoSystems/tagged-base64", tag = "v0.4.0" }
 tide-disco = { git = "https://github.com/EspressoSystems/tide-disco.git", tag = "v0.4.6" }
 toml = "0.8"