diff --git a/Project.toml b/Project.toml
index 81c15e7..a464b71 100644
--- a/Project.toml
+++ b/Project.toml
@@ -16,5 +16,6 @@ TrigPolys = "bbdedc48-cb31-4a37-9fe3-b015aecc8dd3"
 [compat]
 AutoGrad = "1"
 NLopt = "0.6"
+SumOfSquares = "0.6"
 TrigPolys = "0.1"
 julia = "1.6"