diff --git a/Cargo.toml b/Cargo.toml
index ffebdb4c..c7947220 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,7 +8,8 @@ categories = [ "algorithms", "data-structures", "science" ]
 license = "MIT OR Apache-2.0"
 name = "num-bigint"
 repository = "https://github.com/rust-num/num-bigint"
-version = "0.3.2"
+version = "0.4.0-pre"
+publish = false
 readme = "README.md"
 build = "build.rs"
 exclude = ["/bors.toml", "/ci/*", "/.github/*"]