diff --git a/ndk/src/hardware_buffer.rs b/ndk/src/hardware_buffer.rs
index 25a503c5..63849f38 100644
--- a/ndk/src/hardware_buffer.rs
+++ b/ndk/src/hardware_buffer.rs
@@ -210,7 +210,9 @@ impl HardwareBuffer {
             width: desc.width,
             height: desc.height,
             layers: desc.layers,
-            format: desc.format.into(),
+            format: i32::try_from(desc.format)
+                .expect("i32->u32 overflow in HardwareBuffer::describe()")
+                .into(),
             usage: HardwareBufferUsage(ffi::AHardwareBuffer_UsageFlags(desc.usage)),
             stride: desc.stride,
         }
@@ -496,7 +498,9 @@ impl HardwareBufferDesc {
             width: self.width,
             height: self.height,
             layers: self.layers,
-            format: self.format.into(),
+            format: i32::from(self.format)
+                .try_into()
+                .expect("i32->u32 overflow in HardwareBufferDesc::into_native()"),
             usage: self.usage.0 .0,
             stride: self.stride,
             rfu0: 0,
diff --git a/ndk/src/hardware_buffer_format.rs b/ndk/src/hardware_buffer_format.rs
index 4db5d276..555669f5 100644
--- a/ndk/src/hardware_buffer_format.rs
+++ b/ndk/src/hardware_buffer_format.rs
@@ -5,62 +5,66 @@
 use num_enum::{FromPrimitive, IntoPrimitive};
 
 /// Buffer pixel formats.
-#[repr(u32)]
+#[repr(i32)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, FromPrimitive, IntoPrimitive)]
 #[allow(non_camel_case_types)]
 #[non_exhaustive]
 pub enum HardwareBufferFormat {
     /// Matches deprecated [`ffi::ANativeWindow_LegacyFormat::WINDOW_FORMAT_RGBA_8888`].0.
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM")]
-    R8G8B8A8_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM.0,
+    R8G8B8A8_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM.0 as i32,
     /// Matches deprecated [`ffi::ANativeWindow_LegacyFormat::WINDOW_FORMAT_RGBX_8888`].0.
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_R8G8B8X8_UNORM")]
-    R8G8B8X8_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8X8_UNORM.0,
+    R8G8B8X8_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8X8_UNORM.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_R8G8B8_UNORM")]
-    R8G8B8_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8_UNORM.0,
+    R8G8B8_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8_UNORM.0 as i32,
     /// Matches deprecated [`ffi::ANativeWindow_LegacyFormat::WINDOW_FORMAT_RGB_565`].0.
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_R5G6B5_UNORM")]
-    R5G6B5_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R5G6B5_UNORM.0,
+    R5G6B5_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R5G6B5_UNORM.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_R16G16B16A16_FLOAT")]
-    R16G16B16A16_FLOAT = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R16G16B16A16_FLOAT.0,
+    R16G16B16A16_FLOAT =
+        ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R16G16B16A16_FLOAT.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_R10G10B10A2_UNORM")]
-    R10G10B10A2_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R10G10B10A2_UNORM.0,
+    R10G10B10A2_UNORM =
+        ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R10G10B10A2_UNORM.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_BLOB")]
-    BLOB = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_BLOB.0,
+    BLOB = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_BLOB.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_D16_UNORM")]
-    D16_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D16_UNORM.0,
+    D16_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D16_UNORM.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_D24_UNORM")]
-    D24_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D24_UNORM.0,
+    D24_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D24_UNORM.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_D24_UNORM_S8_UINT")]
-    D24_UNORM_S8_UINT = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D24_UNORM_S8_UINT.0,
+    D24_UNORM_S8_UINT =
+        ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D24_UNORM_S8_UINT.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_D32_FLOAT")]
-    D32_FLOAT = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D32_FLOAT.0,
+    D32_FLOAT = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D32_FLOAT.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_D32_FLOAT_S8_UINT")]
-    D32_FLOAT_S8_UINT = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D32_FLOAT_S8_UINT.0,
+    D32_FLOAT_S8_UINT =
+        ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_D32_FLOAT_S8_UINT.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_S8_UINT")]
-    S8_UINT = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_S8_UINT.0,
+    S8_UINT = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_S8_UINT.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_Y8Cb8Cr8_420")]
-    Y8Cb8Cr8_420 = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_Y8Cb8Cr8_420.0,
+    Y8Cb8Cr8_420 = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_Y8Cb8Cr8_420.0 as i32,
     #[cfg(feature = "api-level-26")]
     #[doc(alias = "AHARDWAREBUFFER_FORMAT_YCbCr_P010")]
-    YCbCr_P010 = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_YCbCr_P010.0,
+    YCbCr_P010 = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_YCbCr_P010.0 as i32,
     #[cfg(feature = "api-level-26")]
-    R8_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8_UNORM.0,
+    R8_UNORM = ffi::AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8_UNORM.0 as i32,
 
     #[doc(hidden)]
     #[num_enum(catch_all)]
-    __Unknown(u32),
+    __Unknown(i32),
 }
 
 impl HardwareBufferFormat {
diff --git a/ndk/src/native_activity.rs b/ndk/src/native_activity.rs
index cb889638..b30c49a9 100644
--- a/ndk/src/native_activity.rs
+++ b/ndk/src/native_activity.rs
@@ -216,14 +216,7 @@ impl NativeActivity {
     ///
     /// [`getWindow().setFormat()`]: https://developer.android.com/reference/android/view/Window#setFormat(int)
     pub fn set_window_format(&self, format: HardwareBufferFormat) {
-        unsafe {
-            ffi::ANativeActivity_setWindowFormat(
-                self.ptr.as_ptr(),
-                u32::from(format)
-                    .try_into()
-                    .expect("i32 overflow in set_window_format()"),
-            )
-        }
+        unsafe { ffi::ANativeActivity_setWindowFormat(self.ptr.as_ptr(), format.into()) }
     }
 
     /// Change the window flags of the given activity.
diff --git a/ndk/src/native_window.rs b/ndk/src/native_window.rs
index 2054263d..4a8657f6 100644
--- a/ndk/src/native_window.rs
+++ b/ndk/src/native_window.rs
@@ -104,7 +104,6 @@ impl NativeWindow {
     /// Return the current pixel format ([`HardwareBufferFormat`]) of the window surface.
     pub fn format(&self) -> HardwareBufferFormat {
         let value = unsafe { ffi::ANativeWindow_getFormat(self.ptr.as_ptr()) };
-        let value = u32::try_from(value).unwrap();
         value.into()
     }
 
@@ -123,11 +122,7 @@ impl NativeWindow {
         height: i32,
         format: Option<HardwareBufferFormat>,
     ) -> io::Result<()> {
-        let format = format.map_or(0, |f| {
-            u32::from(f)
-                .try_into()
-                .expect("i32 overflow in set_buffers_geometry")
-        });
+        let format = format.map_or(0i32, |f| f.into());
         let status = unsafe {
             ffi::ANativeWindow_setBuffersGeometry(self.ptr.as_ptr(), width, height, format)
         };
@@ -324,8 +319,7 @@ impl<'a> NativeWindowBufferLockGuard<'a> {
 
     /// The format of the buffer. One of [`HardwareBufferFormat`].
     pub fn format(&self) -> HardwareBufferFormat {
-        let format = u32::try_from(self.buffer.format).unwrap();
-        format.into()
+        self.buffer.format.into()
     }
 
     /// The actual bits.