Index: rfc2047-decoder/Cargo.toml
===================================================================
--- rfc2047-decoder.orig/Cargo.toml
+++ rfc2047-decoder/Cargo.toml
@@ -41,7 +41,7 @@ repository = "https://github.com/TornaxO
 name = "rfc2047_decoder"
 
 [dependencies.base64]
-version = "0.21"
+version = ">= 0.21, < 1.0"
 
 [dependencies.charset]
 version = "0.1"
