diff --git a/Project.toml b/Project.toml
index 3318b46d..5c7b0313 100644
--- a/Project.toml
+++ b/Project.toml
@@ -24,7 +24,7 @@ DiffTests = "0.0.1, 0.1"
 LogExpFunctions = "0.3"
 NaNMath = "0.2.2, 0.3"
 Preferences = "1"
-SpecialFunctions = "0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.10, 1.0"
+SpecialFunctions = "0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.10, 1.0, 2"
 StaticArrays = "0.8.3, 0.9, 0.10, 0.11, 0.12, 1.0"
 julia = "1"