diff --git a/Project.toml b/Project.toml
index 2a5866d..3d15074 100644
--- a/Project.toml
+++ b/Project.toml
@@ -20,7 +20,7 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 DoubleFloats = "1"
 FFTW = "^1"
 GenericSchur = "0.4, 0.5"
-Polynomials = "^1, 2.0, 3"
+Polynomials = "^1, 2.0, 3, 4"
 RecursiveArrayTools = "2, 3"
 Reexport = "^0.2, 1.0"
 SciMLBase = "1"