diff --git a/Cargo.toml b/Cargo.toml
index 13e047c..66bc36a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -29,7 +29,7 @@ mach = "0.3"
 libc = "0.2"
 
 [target.'cfg(target_os = "windows")'.dependencies.windows-sys]
-version = "0.52"
+version = "0.59"
 features = [
     "Win32_Foundation",
     "Win32_System_LibraryLoader",
diff --git a/src/lib.rs b/src/lib.rs
index 6006f79..de4f807 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -454,7 +454,7 @@ pub extern "C" fn atp_set_real_time_limit(audio_buffer_frames: u32,
 /// # Arguments
 ///
 /// * `audio_buffer_frames` - the exact or an upper limit on the number of frames that have to be
-/// rendered each callback, or 0 for a sensible default value.
+///   rendered each callback, or 0 for a sensible default value.
 /// * `audio_samplerate_hz` - the sample-rate for this audio stream, in Hz.
 ///
 /// # Return value
@@ -476,7 +476,7 @@ pub fn promote_current_thread_to_real_time(
 /// # Arguments
 ///
 /// * `handle` - An opaque struct returned from a successful call to
-/// `promote_current_thread_to_real_time`.
+///   `promote_current_thread_to_real_time`.
 ///
 /// # Return value
 ///
@@ -496,7 +496,7 @@ pub struct atp_handle(RtPriorityHandle);
 /// # Arguments
 ///
 /// * `audio_buffer_frames` - the exact or an upper limit on the number of frames that have to be
-/// rendered each callback, or 0 for a sensible default value.
+///   rendered each callback, or 0 for a sensible default value.
 /// * `audio_samplerate_hz` - the sample-rate for this audio stream, in Hz.
 ///
 /// # Return value
@@ -524,7 +524,7 @@ pub extern "C" fn atp_promote_current_thread_to_real_time(
 /// # Arguments
 ///
 /// * `atp_handle` - An opaque struct returned from a successful call to
-/// `atp_promote_current_thread_to_real_time`.
+///   `atp_promote_current_thread_to_real_time`.
 ///
 /// # Return value
 ///
@@ -554,7 +554,7 @@ pub unsafe extern "C" fn atp_demote_current_thread_from_real_time(handle: *mut a
 /// # Arguments
 ///
 /// * `atp_handle` - An opaque struct returned from a successful call to
-/// `atp_promote_current_thread_to_real_time`.
+///   `atp_promote_current_thread_to_real_time`.
 ///
 /// # Return value
 ///
diff --git a/src/rt_win.rs b/src/rt_win.rs
index 480c5bd..237b180 100644
--- a/src/rt_win.rs
+++ b/src/rt_win.rs
@@ -94,14 +94,16 @@ mod avrt_lib {
         pub(super) fn try_new() -> Result<Self, WIN32_ERROR> {
             let module = OwnedLibrary::try_new(w!("avrt.dll"))?;
             let av_set_mm_thread_characteristics_w = unsafe {
-                std::mem::transmute::<_, AvSetMmThreadCharacteristicsWFn>(
-                    module.get_proc(s!("AvSetMmThreadCharacteristicsW"))?,
-                )
+                std::mem::transmute::<
+                    unsafe extern "system" fn() -> isize,
+                    AvSetMmThreadCharacteristicsWFn,
+                >(module.get_proc(s!("AvSetMmThreadCharacteristicsW"))?)
             };
             let av_revert_mm_thread_characteristics = unsafe {
-                std::mem::transmute::<_, AvRevertMmThreadCharacteristicsFn>(
-                    module.get_proc(s!("AvRevertMmThreadCharacteristics"))?,
-                )
+                std::mem::transmute::<
+                    unsafe extern "system" fn() -> isize,
+                    AvRevertMmThreadCharacteristicsFn,
+                >(module.get_proc(s!("AvRevertMmThreadCharacteristics"))?)
             };
             Ok(Self {
                 module,
@@ -135,7 +137,7 @@ mod avrt_lib {
             let task_handle = unsafe {
                 (self.av_set_mm_thread_characteristics_w)(task_name, &mut mmcss_task_index)
             };
-            win32_error_if(task_handle == 0)?;
+            win32_error_if(task_handle.is_null())?;
             Ok((mmcss_task_index, task_handle))
         }
 
@@ -172,7 +174,7 @@ mod win32_utils {
     impl OwnedLibrary {
         pub(super) fn try_new(lib_file_name: PCWSTR) -> Result<Self, WIN32_ERROR> {
             let module = unsafe { LoadLibraryW(lib_file_name) };
-            win32_error_if(module == 0)?;
+            win32_error_if(module.is_null())?;
             Ok(Self(module))
         }
 
@@ -199,6 +201,9 @@ mod win32_utils {
             }
         }
     }
+
+    unsafe impl Send for OwnedLibrary {}
+    unsafe impl Sync for OwnedLibrary {}
 }
 
 #[cfg(test)]