diff --git a/Project.toml b/Project.toml
index a50576af..27311d44 100644
--- a/Project.toml
+++ b/Project.toml
@@ -19,7 +19,7 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 SuiteSparse = "4607b0f0-06f3-5cda-b6b1-a6196a1729e9"
 
 [compat]
-Compat = "3"
+Compat = "3, 4"
 ExprTools = "^0.1"
 GeometryBasics = "^0.3, 0.4"
 NearestNeighbors = "0.4"