diff --git a/Cargo.toml b/Cargo.toml
index 66e65be..cc98f2b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,7 +14,7 @@ edition = "2021"
 fixedbitset = "0.4.0"
 encoding = "0.2"
 log = "0.4"
-smptera-format-identifiers-rust = "0.3.0"
+smptera-format-identifiers-rust = "0.4.0"
 
 [dev-dependencies]
 assert_matches = "1.5.0"