diff --git a/Project.toml b/Project.toml
index ee2a6a6..462a1da 100644
--- a/Project.toml
+++ b/Project.toml
@@ -13,7 +13,7 @@ SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
 [compat]
-Ipopt = "0.6.5 - 0.7"
+Ipopt = "0.6.5 - 0.7, 0.9"
 MathProgBase = "0.7"
 julia = "1"