diff --git a/Project.toml b/Project.toml
index bc61ca9..c446f45 100644
--- a/Project.toml
+++ b/Project.toml
@@ -39,7 +39,7 @@ ProgressMeter = "1"
 RecipesBase = "1"
 RecursiveArrayTools = "2"
 Reexport = "1"
-Sundials = "4.16 - 4.19.3"
+Sundials = "4.16 - 4.19.3, 4"
 XLSX = "0.7, 0.8"
 julia = "1.6"