diff --git a/Project.toml b/Project.toml
index 12f1fad..b3f9966 100644
--- a/Project.toml
+++ b/Project.toml
@@ -21,7 +21,7 @@ JSON = "0.21"
 Mustache = "0.4.1, 0.5, 1"
 Plots = "0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29"
 Requires = "1.0"
-YAML = "0.3"
+YAML = "0.3, 0.4"
 julia = "1"
 
 [extras]