diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3450b770..a3dea2e2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -77,7 +77,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [1.19.0, 1.20.0, 1.21.0, 1.25.0, 1.26.0, 1.34.0]
+        rust: [1.20.0, 1.21.0, 1.25.0, 1.26.0, 1.34.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v3
diff --git a/README.md b/README.md
index a049250b..387a218d 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,12 @@
-# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.19+]][Rust 1.19] [![serde_derive: rustc 1.56+]][Rust 1.56]
+# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.20+]][Rust 1.20] [![serde_derive: rustc 1.56+]][Rust 1.56]
 
 [Build Status]: https://img.shields.io/github/actions/workflow/status/serde-rs/serde/ci.yml?branch=master
 [actions]: https://github.com/serde-rs/serde/actions?query=branch%3Amaster
 [Latest Version]: https://img.shields.io/crates/v/serde.svg
 [crates.io]: https://crates.io/crates/serde
-[serde: rustc 1.19+]: https://img.shields.io/badge/serde-rustc_1.19+-lightgray.svg
+[serde: rustc 1.20+]: https://img.shields.io/badge/serde-rustc_1.20+-lightgray.svg
 [serde_derive: rustc 1.56+]: https://img.shields.io/badge/serde_derive-rustc_1.56+-lightgray.svg
-[Rust 1.19]: https://blog.rust-lang.org/2017/07/20/Rust-1.19.html
+[Rust 1.20]: https://blog.rust-lang.org/2017/08/31/Rust-1.20.html
 [Rust 1.56]: https://blog.rust-lang.org/2021/10/21/Rust-1.56.0.html
 
 **Serde is a framework for *ser*ializing and *de*serializing Rust data structures efficiently and generically.**
diff --git a/serde/Cargo.toml b/serde/Cargo.toml
index b9959cf0..b752f407 100644
--- a/serde/Cargo.toml
+++ b/serde/Cargo.toml
@@ -11,7 +11,7 @@ keywords = ["serde", "serialization", "no_std"]
 license = "MIT OR Apache-2.0"
 readme = "crates-io.md"
 repository = "https://github.com/serde-rs/serde"
-rust-version = "1.19"
+rust-version = "1.20"
 
 [dependencies]
 serde_derive = { version = "=1.0.179", optional = true, path = "../serde_derive" }
diff --git a/serde/build.rs b/serde/build.rs
index 66f3b6ed..7a5ce83a 100644
--- a/serde/build.rs
+++ b/serde/build.rs
@@ -16,11 +16,9 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // CString::into_boxed_c_str and PathBuf::into_boxed_path stabilized in Rust 1.20:
-    // https://doc.rust-lang.org/std/ffi/struct.CString.html#method.into_boxed_c_str
+    // PathBuf::into_boxed_path stabilized in Rust 1.20:
     // https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.into_boxed_path
     if minor < 20 {
-        println!("cargo:rustc-cfg=no_de_boxed_c_str");
         println!("cargo:rustc-cfg=no_de_boxed_path");
     }
 
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 5dba42b2..b362a216 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -747,10 +747,7 @@ macro_rules! forwarded_impl {
     }
 }
 
-#[cfg(all(
-    any(feature = "std", all(not(no_core_cstr), feature = "alloc")),
-    not(no_de_boxed_c_str)
-))]
+#[cfg(any(feature = "std", all(not(no_core_cstr), feature = "alloc")))]
 forwarded_impl!((), Box<CStr>, CString::into_boxed_c_str);
 
 forwarded_impl!((T), Reverse<T>, Reverse);