diff --git a/Project.toml b/Project.toml
index 8b43829..a43a84f 100644
--- a/Project.toml
+++ b/Project.toml
@@ -10,7 +10,7 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
 
 [compat]
-Unitful = "0.15, ~1.6"
+Unitful = "0.15, ~1.6, 1"
 julia = "~1.0.4, 1.1.1"
 
 [extras]