diff --git a/Project.toml b/Project.toml
index 89963a9..e93d424 100644
--- a/Project.toml
+++ b/Project.toml
@@ -11,6 +11,7 @@ UnitfulAstro = "6112ee07-acf9-5e0f-b108-d242c714bf9f"
 WCS = "15f3aee2-9e10-537f-b834-a6fb8bdb944d"
 
 [compat]
+Unitful = "1"
 julia = "1"
 
 [extras]