diff --git a/Project.toml b/Project.toml
index e901697bc..218c9a2df 100644
--- a/Project.toml
+++ b/Project.toml
@@ -37,6 +37,7 @@ VegaLite = "112f6efa-9a02-5b7d-90c0-432ed331239a"
 
 [compat]
 CSVFiles = "0.16.0"
+Classes = "0.1"
 Compose = "0.7"
 DataFrames = "0.19.1"
 Electron = "1.1"