diff --git a/psa-crypto-sys/build.rs b/psa-crypto-sys/build.rs
index 9d5232e..5441c77 100644
--- a/psa-crypto-sys/build.rs
+++ b/psa-crypto-sys/build.rs
@@ -171,6 +171,7 @@ mod common {
             .clang_arg(format!("-I{}", mbed_include_dir))
             .header("src/c/shim.h")
             .blocklist_type("max_align_t")
+            .use_core()
             .generate_comments(false)
             .size_t_is_usize(true);
 
diff --git a/psa-crypto-sys/src/lib.rs b/psa-crypto-sys/src/lib.rs
index a84ed98..c412825 100644
--- a/psa-crypto-sys/src/lib.rs
+++ b/psa-crypto-sys/src/lib.rs
@@ -7,6 +7,7 @@
 //! You can find the API
 //! [here](https://developer.arm.com/architectures/security-architectures/platform-security-architecture/documentation).
 
+#![no_std]
 // This one is hard to avoid.
 #![allow(clippy::multiple_crate_versions)]
 #![allow(clippy::missing_safety_doc)]
diff --git a/psa-crypto/Cargo.toml b/psa-crypto/Cargo.toml
index 485c9b8..7ca0fda 100644
--- a/psa-crypto/Cargo.toml
+++ b/psa-crypto/Cargo.toml
@@ -15,7 +15,7 @@ rust-version = "1.66.0"
 psa-crypto-sys = { path = "../psa-crypto-sys", version = "0.12.0", default-features = false }
 log = "0.4.20"
 serde = { version = "1.0.115", features = ["derive"], default-features = false }
-zeroize = { version = "1.4.3", features = ["zeroize_derive"] }
+zeroize = { version = "1.4.3", features = ["zeroize_derive"], default-features = false }
 
 [dev-dependencies]
 rsa = { version = "0.5.0", features = ["alloc"] }