diff --git a/src/ReinforcementLearningBase/Project.toml b/src/ReinforcementLearningBase/Project.toml
index 13a6fe64b..4848469cd 100644
--- a/src/ReinforcementLearningBase/Project.toml
+++ b/src/ReinforcementLearningBase/Project.toml
@@ -11,7 +11,7 @@ Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
-AbstractTrees = "0.3"
+AbstractTrees = "0.3, 0.4"
 CommonRLInterface = "0.3"
 julia = "1.3"