diff --git a/Project.toml b/Project.toml
index eb01a1e..317bdec 100644
--- a/Project.toml
+++ b/Project.toml
@@ -27,7 +27,7 @@ Plots = "1.26"
 RecipesBase = "1.2.1"
 Reexport = "0.2.0"
 Roots = "1.3"
-SpecialFunctions = "1.6.2"
+SpecialFunctions = "1.6.2, 2"
 ViscousFlow = "0.5.1"
 julia = "1.6"