diff --git a/Cargo.toml b/Cargo.toml
index 49e11cb..c904ec1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
-[project]
+[package]
 name = "probe"
-version = "0.3.0"
+version = "0.4.0"
 authors = ["Josh Stone <cuviper@gmail.com>"]
 description = "Static instrumentation probes"
 documentation = "https://docs.rs/probe/"
@@ -8,6 +8,7 @@ homepage = "https://github.com/cuviper/rust-libprobe"
 repository = "https://github.com/cuviper/rust-libprobe"
 license = "Apache-2.0 OR MIT"
 edition = "2021"
+rust-version = "1.66"
 exclude = ["/.github/**"]
 
 [lib]
diff --git a/README.md b/README.md
index 2cffcfc..d8cb9c2 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # libprobe: Static probes for Rust
 
 [![probe crate](https://img.shields.io/crates/v/probe.svg)](https://crates.io/crates/probe)
-![minimum rustc 1.59](https://img.shields.io/badge/rustc-1.59+-red.svg)
+![minimum rustc 1.66](https://img.shields.io/badge/rustc-1.66+-red.svg)
 [![probe documentation](https://docs.rs/probe/badge.svg)](https://docs.rs/probe)
 [![build status](https://github.com/cuviper/rust-libprobe/workflows/CI/badge.svg)](https://github.com/cuviper/rust-libprobe/actions)
 
@@ -20,7 +20,7 @@ The recommended way to use it is to add a line into your Cargo.toml such as:
 
 ```toml
 [dependencies]
-probe = "0.3"
+probe = "0.4"
 ```
 
 Then `use probe::probe;` in your code and insert macro calls wherever you want