diff --git a/Project.toml b/Project.toml
index 71c4de7e..83834ab1 100644
--- a/Project.toml
+++ b/Project.toml
@@ -26,7 +26,7 @@ UnitfulAstro = "6112ee07-acf9-5e0f-b108-d242c714bf9f"
 [compat]
 OceanGrids = "0.1.1"
 WorldOceanAtlasTools = "0.3"
-Flatten = "0.2.1+"
+Flatten = "0.2.1"
 julia = "1.1"
 
 [extras]