diff --git a/src/isolate.rs b/src/isolate.rs
index 33d8db7802..2264179f79 100644
--- a/src/isolate.rs
+++ b/src/isolate.rs
@@ -195,12 +195,18 @@ pub type PrepareStackTraceCallback<'s> = extern "C" fn(
 ) -> *mut *const Value;
 
 // System V ABI: MaybeLocal<Value> returned in a register.
+// System V i386 ABI: Local<Value> returned in hidden pointer (struct).
 #[cfg(not(target_os = "windows"))]
-pub type PrepareStackTraceCallback<'s> = extern "C" fn(
-  Local<'s, Context>,
-  Local<'s, Value>,
-  Local<'s, Array>,
-) -> *const Value;
+#[repr(C)]
+pub struct PrepareStackTraceCallbackRet(*const Value);
+
+#[cfg(not(target_os = "windows"))]
+pub type PrepareStackTraceCallback<'s> =
+  extern "C" fn(
+    Local<'s, Context>,
+    Local<'s, Value>,
+    Local<'s, Array>,
+  ) -> PrepareStackTraceCallbackRet;
 
 extern "C" {
   fn v8__Isolate__New(params: *const raw::CreateParams) -> *mut Isolate;
@@ -1228,13 +1234,13 @@ where
     f.to_c_fn()
   }
 
-  // System V ABI: MaybeLocal<Value> returned in a register.
+  // System V ABI
   #[cfg(not(target_os = "windows"))]
   fn mapping() -> Self {
     let f = |context, error, sites| {
       let mut scope: CallbackScope = unsafe { CallbackScope::new(context) };
       let r = (F::get())(&mut scope, error, sites);
-      &*r as *const _
+      PrepareStackTraceCallbackRet(&*r as *const _)
     };
     f.to_c_fn()
   }
@@ -1282,7 +1288,7 @@ impl BuildHasher for BuildTypeIdHasher {
 
 const _: () = {
   assert!(size_of::<TypeId>() == size_of::<u64>());
-  assert!(align_of::<TypeId>() == size_of::<u64>());
+  assert!(align_of::<TypeId>() == align_of::<u64>());
 };
 
 pub(crate) struct RawSlot {
diff --git a/src/module.rs b/src/module.rs
index e5f2ca14c0..420d9b8461 100644
--- a/src/module.rs
+++ b/src/module.rs
@@ -38,14 +38,18 @@ use crate::Value;
 ///   }
 /// ```
 
-// System V AMD64 ABI: Local<Module> returned in a register.
+// System V ABI
+#[cfg(not(target_os = "windows"))]
+#[repr(C)]
+pub struct ResolveModuleCallbackRet(*const Module);
+
 #[cfg(not(target_os = "windows"))]
 pub type ResolveModuleCallback<'a> = extern "C" fn(
   Local<'a, Context>,
   Local<'a, String>,
   Local<'a, FixedArray>,
   Local<'a, Module>,
-) -> *const Module;
+) -> ResolveModuleCallbackRet;
 
 // Windows x64 ABI: Local<Module> returned on the stack.
 #[cfg(target_os = "windows")]
@@ -70,9 +74,11 @@ where
   #[cfg(not(target_os = "windows"))]
   fn mapping() -> Self {
     let f = |context, specifier, import_assertions, referrer| {
-      (F::get())(context, specifier, import_assertions, referrer)
-        .map(|r| -> *const Module { &*r })
-        .unwrap_or(null())
+      ResolveModuleCallbackRet(
+        (F::get())(context, specifier, import_assertions, referrer)
+          .map(|r| -> *const Module { &*r })
+          .unwrap_or(null()),
+      )
     };
     f.to_c_fn()
   }
@@ -90,10 +96,17 @@ where
   }
 }
 
-// System V AMD64 ABI: Local<Value> returned in a register.
+// System V ABI.
+#[cfg(not(target_os = "windows"))]
+#[repr(C)]
+pub struct SyntheticModuleEvaluationStepsRet(*const Value);
+
 #[cfg(not(target_os = "windows"))]
 pub type SyntheticModuleEvaluationSteps<'a> =
-  extern "C" fn(Local<'a, Context>, Local<'a, Module>) -> *const Value;
+  extern "C" fn(
+    Local<'a, Context>,
+    Local<'a, Module>,
+  ) -> SyntheticModuleEvaluationStepsRet;
 
 // Windows x64 ABI: Local<Value> returned on the stack.
 #[cfg(target_os = "windows")]
@@ -112,9 +125,11 @@ where
   #[cfg(not(target_os = "windows"))]
   fn mapping() -> Self {
     let f = |context, module| {
-      (F::get())(context, module)
-        .map(|r| -> *const Value { &*r })
-        .unwrap_or(null())
+      SyntheticModuleEvaluationStepsRet(
+        (F::get())(context, module)
+          .map(|r| -> *const Value { &*r })
+          .unwrap_or(null()),
+      )
     };
     f.to_c_fn()
   }
@@ -139,8 +154,8 @@ extern "C" {
   fn v8__Module__SourceOffsetToLocation(
     this: *const Module,
     offset: int,
-    out: *mut MaybeUninit<Location>,
-  ) -> Location;
+    out: *mut Location,
+  );
   fn v8__Module__GetModuleNamespace(this: *const Module) -> *const Value;
   fn v8__Module__GetIdentityHash(this: *const Module) -> int;
   fn v8__Module__ScriptId(this: *const Module) -> int;
@@ -240,7 +255,7 @@ impl Module {
   pub fn source_offset_to_location(&self, offset: int) -> Location {
     let mut out = MaybeUninit::<Location>::uninit();
     unsafe {
-      v8__Module__SourceOffsetToLocation(self, offset, &mut out);
+      v8__Module__SourceOffsetToLocation(self, offset, out.as_mut_ptr());
       out.assume_init()
     }
   }
diff --git a/tests/test_api.rs b/tests/test_api.rs
index a1e83d06b4..6f92e75124 100644
--- a/tests/test_api.rs
+++ b/tests/test_api.rs
@@ -4012,9 +4012,14 @@ fn typed_array_constructors() {
   let t = v8::BigInt64Array::new(scope, ab, 0, 0).unwrap();
   assert!(t.is_big_int64_array());
 
-  // TypedArray::max_length() ought to be >= 2^30 < 2^32
+  // TypedArray::max_length() ought to be >= 2^30 < 2^32 in 64 bits
+  #[cfg(target_pointer_width = "64")]
   assert!(((2 << 30)..(2 << 32)).contains(&v8::TypedArray::max_length()));
 
+  // TypedArray::max_length() ought to be >= 2^28 < 2^30 in 32 bits
+  #[cfg(target_pointer_width = "32")]
+  assert!(((2 << 28)..(2 << 30)).contains(&v8::TypedArray::max_length()));
+
   // v8::ArrayBuffer::new raises a fatal if the length is > kMaxLength, so we test this behavior
   // through the JS side of things, where a non-fatal RangeError is thrown in such cases.
   {