diff --git a/Cargo.toml b/Cargo.toml
index 8a9edb5..c1ad329 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,7 +17,7 @@ serde = "1.0"
 serde_derive = "1.0"
 hex-slice = "0.1.4"
 url = "2.1.1"
-smptera-format-identifiers-rust = "0.3.0"
+smptera-format-identifiers-rust = "0.4.0"
 log = "0.4"
 
 [dev-dependencies]