diff --git a/crates/rb-sys-build/src/utils.rs b/crates/rb-sys-build/src/utils.rs
index dc768ec7..1e3e1272 100644
--- a/crates/rb-sys-build/src/utils.rs
+++ b/crates/rb-sys-build/src/utils.rs
@@ -35,6 +35,7 @@ macro_rules! memoize {
     ($type:ty: $val:expr) => {{
         static INIT: std::sync::Once = std::sync::Once::new();
         static mut VALUE: Option<$type> = None;
+        #[allow(static_mut_refs)]
         unsafe {
             INIT.call_once(|| {
                 VALUE = Some($val);
diff --git a/crates/rb-sys/Cargo.toml b/crates/rb-sys/Cargo.toml
index 6e94ca65..30853e46 100644
--- a/crates/rb-sys/Cargo.toml
+++ b/crates/rb-sys/Cargo.toml
@@ -17,14 +17,11 @@ rust-version = "1.65"
 rb-sys-build = { version = "0.9.103", path = "../rb-sys-build" }
 
 [dev-dependencies]
-rb-sys = { path = ".", features = [
-  "link-ruby",
-  "stable-api-compiled-fallback",
-] }
+rb-sys = { path = ".", features = ["link-ruby"] }
 rusty-fork = "0.3.0"
 
 [features]
-default = []
+default = ["stable-api-compiled-fallback"]
 link-ruby = []
 fuzz = []
 no-link-ruby = []
@@ -57,4 +54,4 @@ unexpected_cfgs = { level = "warn", check-cfg = [
   "cfg(rb_sys_gem)",
   "cfg(rb_sys_use_stable_api_compiled_fallback)",
   "cfg(rb_sys_force_stable_api_compiled)",
-] }
\ No newline at end of file
+] }
diff --git a/crates/rb-sys/src/stable_api.rs b/crates/rb-sys/src/stable_api.rs
index 10b34f9c..42438289 100644
--- a/crates/rb-sys/src/stable_api.rs
+++ b/crates/rb-sys/src/stable_api.rs
@@ -61,11 +61,21 @@ pub trait StableApiDefinition {
     /// Get the class from a VALUE which contains an RBasic struct.
     ///
     /// `VALUE` is a valid pointer to a non-immediate object.
+    ///
+    /// # Safety
+    /// This function is unsafe because it dereferences a raw pointer to get
+    /// access to underlying RBasic struct. The caller must ensure that the
+    /// `VALUE` is a valid pointer to an RBasic struct.
     unsafe fn rbasic_class(&self, obj: VALUE) -> Option<NonNull<VALUE>>;
 
     /// Checks if the given object is frozen.
     ///
     /// `VALUE` is a valid pointer to a non-immediate object.
+    ///
+    /// # Safety
+    /// This function is unsafe because it may dereference a raw pointer to get
+    /// access to underlying RBasic struct. The caller must ensure that the
+    /// `VALUE` is a valid pointer to an RBasic struct.
     unsafe fn frozen_p(&self, obj: VALUE) -> bool;
 
     /// Tests if a bignum is positive.
@@ -82,6 +92,7 @@ pub trait StableApiDefinition {
     /// This function is unsafe because it dereferences a raw pointer to get
     /// access to underlying RBasic struct. The caller must ensure that the
     /// `VALUE` is a valid pointer to a bignum.
+    #[inline]
     unsafe fn bignum_negative_p(&self, obj: VALUE) -> bool {
         !self.bignum_positive_p(obj)
     }
diff --git a/examples/rust_reverse/ext/rust_reverse/src/lib.rs b/examples/rust_reverse/ext/rust_reverse/src/lib.rs
index 5001e154..236af89c 100644
--- a/examples/rust_reverse/ext/rust_reverse/src/lib.rs
+++ b/examples/rust_reverse/ext/rust_reverse/src/lib.rs
@@ -1,3 +1,5 @@
+#![allow(clippy::manual_c_str_literals)]
+
 use rb_sys::tracking_allocator::ManuallyTracked;
 use rb_sys::*;
 use std::os::raw::c_long;