diff --git a/gc/default/default.c b/gc/default/default.c
index af386a9793ae1d..7c10cc33063b0c 100644
--- a/gc/default/default.c
+++ b/gc/default/default.c
@@ -4377,7 +4377,7 @@ gc_grey(rb_objspace_t *objspace, VALUE obj)
 static inline void
 gc_mark_check_t_none(rb_objspace_t *objspace, VALUE obj)
 {
-    if (RB_UNLIKELY(RB_TYPE_P(obj, T_NONE))) {
+    if (RB_UNLIKELY(BUILTIN_TYPE(obj) == T_NONE)) {
         enum {info_size = 256};
         char obj_info_buf[info_size];
         rb_raw_obj_info(obj_info_buf, info_size, obj);
diff --git a/test/ruby/test_namespace.rb b/test/ruby/test_namespace.rb
index af308ab15c25e3..5661a98ca2b5f1 100644
--- a/test/ruby/test_namespace.rb
+++ b/test/ruby/test_namespace.rb
@@ -552,7 +552,7 @@ def test_prelude_gems_and_loaded_features
 
       # No additional warnings except for experimental warnings
       assert_includes error.join("\n"), EXPERIMENTAL_WARNINGS
-      assert_equal error.size, 2
+      assert_equal 2, error.size
 
       assert_includes output.grep(/^before:/).join("\n"), '/bundled_gems.rb'
       assert_includes output.grep(/^before:/).join("\n"), '/error_highlight.rb'
@@ -574,7 +574,7 @@ def test_prelude_gems_and_loaded_features_with_disable_gems
       end;
 
       assert_includes error.join("\n"), EXPERIMENTAL_WARNINGS
-      assert_equal error.size, 2
+      assert_equal 2, error.size
 
       refute_includes output.grep(/^before:/).join("\n"), '/bundled_gems.rb'
       refute_includes output.grep(/^before:/).join("\n"), '/error_highlight.rb'
diff --git a/zjit/bindgen/src/main.rs b/zjit/bindgen/src/main.rs
index 77d482db4e9d97..43fec090149ef8 100644
--- a/zjit/bindgen/src/main.rs
+++ b/zjit/bindgen/src/main.rs
@@ -130,7 +130,7 @@ fn main() {
         .allowlist_function("rb_singleton_class")
         .allowlist_function("rb_define_class")
         .allowlist_function("rb_class_get_superclass")
-        .allowlist_function("rb_gc_disable_no_rest")
+        .allowlist_function("rb_gc_disable")
         .allowlist_function("rb_gc_enable")
         .allowlist_function("rb_gc_mark")
         .allowlist_function("rb_gc_mark_movable")
diff --git a/zjit/src/backend/arm64/mod.rs b/zjit/src/backend/arm64/mod.rs
index 6750926b35daa1..74b5210f0fb0a6 100644
--- a/zjit/src/backend/arm64/mod.rs
+++ b/zjit/src/backend/arm64/mod.rs
@@ -692,10 +692,10 @@ impl Assembler {
     /// need to be split with registers after `alloc_regs`, e.g. for `compile_side_exits`, so this
     /// splits them and uses scratch registers for it.
     fn arm64_split_with_scratch_reg(mut self) -> Assembler {
-        let mut iterator = self.insns.into_iter().enumerate().peekable();
+        let iterator = self.insns.into_iter().enumerate().peekable();
         let mut asm = Assembler::new_with_label_names(take(&mut self.label_names), self.live_ranges.len(), true);
 
-        while let Some((_, mut insn)) = iterator.next() {
+        for (_, mut insn) in iterator {
             match &mut insn {
                 // For compile_side_exits, support splitting simple C arguments here
                 Insn::CCall { opnds, .. } if !opnds.is_empty() => {
diff --git a/zjit/src/cruby.rs b/zjit/src/cruby.rs
index 4eb1d3a17c836e..dca4d9180556e8 100644
--- a/zjit/src/cruby.rs
+++ b/zjit/src/cruby.rs
@@ -897,7 +897,7 @@ where
     //   2. If we yield to the GC while compiling, it re-enters our mark and update functions.
     //      This breaks `&mut` exclusivity since mark functions derive fresh `&mut` from statics
     //      while there is a stack frame below it that has an overlapping `&mut`. That's UB.
-    let gc_disabled_pre_call = unsafe { rb_gc_disable_no_rest() }.test();
+    let gc_disabled_pre_call = unsafe { rb_gc_disable() }.test();
 
     let ret = match catch_unwind(func) {
         Ok(result) => result,
diff --git a/zjit/src/cruby_bindings.inc.rs b/zjit/src/cruby_bindings.inc.rs
index 6a6263ab15110a..17cda12a0b6204 100644
--- a/zjit/src/cruby_bindings.inc.rs
+++ b/zjit/src/cruby_bindings.inc.rs
@@ -746,6 +746,7 @@ unsafe extern "C" {
     pub fn rb_gc_mark_movable(obj: VALUE);
     pub fn rb_gc_location(obj: VALUE) -> VALUE;
     pub fn rb_gc_enable() -> VALUE;
+    pub fn rb_gc_disable() -> VALUE;
     pub fn rb_gc_writebarrier(old: VALUE, young: VALUE);
     pub fn rb_class_get_superclass(klass: VALUE) -> VALUE;
     pub static mut rb_cObject: VALUE;
@@ -877,7 +878,6 @@ unsafe extern "C" {
         buff_size: usize,
         obj: VALUE,
     ) -> *const ::std::os::raw::c_char;
-    pub fn rb_gc_disable_no_rest() -> VALUE;
     pub fn rb_ec_stack_check(ec: *mut rb_execution_context_struct) -> ::std::os::raw::c_int;
     pub fn rb_gc_writebarrier_remember(obj: VALUE);
     pub fn rb_shape_id_offset() -> i32;