--- a/Cargo.toml
+++ b/Cargo.toml
@@ -152,7 +152,7 @@ default-features = false
 version = "1.6.1"
 
 [dependencies.heck]
-version = "0.5"
+version = ">=0.4"
 
 [dependencies.hex]
 version = "0.4.3"
