diff --git a/Project.toml b/Project.toml
index 4517961..176b73a 100644
--- a/Project.toml
+++ b/Project.toml
@@ -9,7 +9,8 @@ LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 
 [compat]
-julia = "1.4"
+julia = "1.3"
+Combinatorics = "1"
 
 [extras]
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"