diff --git a/gdk-pixbuf/src/subclass/pixbuf_animation.rs b/gdk-pixbuf/src/subclass/pixbuf_animation.rs
index 4a014d8be908..d51da8c3866b 100644
--- a/gdk-pixbuf/src/subclass/pixbuf_animation.rs
+++ b/gdk-pixbuf/src/subclass/pixbuf_animation.rs
@@ -13,7 +13,10 @@ use glib::{prelude::*, subclass::prelude::*, translate::*};
 
 use crate::{ffi, Pixbuf, PixbufAnimation, PixbufAnimationIter};
 
-pub trait PixbufAnimationImpl: ObjectImpl {
+pub trait PixbufAnimationImpl: ObjectImpl
+where
+    <Self as ObjectSubclass>::Type: IsA<PixbufAnimation>,
+{
     fn is_static_image(&self) -> bool {
         self.parent_is_static_image()
     }
@@ -32,11 +35,18 @@ pub trait PixbufAnimationImpl: ObjectImpl {
 }
 
 mod sealed {
+    use glib::{prelude::*, subclass::prelude::*};
     pub trait Sealed {}
-    impl<T: super::PixbufAnimationImplExt> Sealed for T {}
+    impl<T: super::PixbufAnimationImplExt> Sealed for T where
+        <T as ObjectSubclass>::Type: IsA<super::PixbufAnimation>
+    {
+    }
 }
 
-pub trait PixbufAnimationImplExt: sealed::Sealed + ObjectSubclass {
+pub trait PixbufAnimationImplExt: sealed::Sealed + ObjectSubclass
+where
+    <Self as ObjectSubclass>::Type: IsA<PixbufAnimation>,
+{
     fn parent_is_static_image(&self) -> bool {
         unsafe {
             let data = Self::type_data();
@@ -116,9 +126,15 @@ pub trait PixbufAnimationImplExt: sealed::Sealed + ObjectSubclass {
     }
 }
 
-impl<T: PixbufAnimationImpl> PixbufAnimationImplExt for T {}
+impl<T: PixbufAnimationImpl> PixbufAnimationImplExt for T where
+    <Self as ObjectSubclass>::Type: IsA<PixbufAnimation>
+{
+}
 
-unsafe impl<T: PixbufAnimationImpl> IsSubclassable<T> for PixbufAnimation {
+unsafe impl<T: PixbufAnimationImpl> IsSubclassable<T> for PixbufAnimation
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimation>,
+{
     fn class_init(class: &mut ::glib::Class<Self>) {
         Self::parent_class_init::<T>(class);
 
@@ -132,7 +148,10 @@ unsafe impl<T: PixbufAnimationImpl> IsSubclassable<T> for PixbufAnimation {
 
 unsafe extern "C" fn animation_is_static_image<T: PixbufAnimationImpl>(
     ptr: *mut ffi::GdkPixbufAnimation,
-) -> glib::ffi::gboolean {
+) -> glib::ffi::gboolean
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimation>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
@@ -143,7 +162,9 @@ unsafe extern "C" fn animation_get_size<T: PixbufAnimationImpl>(
     ptr: *mut ffi::GdkPixbufAnimation,
     width_ptr: *mut libc::c_int,
     height_ptr: *mut libc::c_int,
-) {
+) where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimation>,
+{
     if width_ptr.is_null() && height_ptr.is_null() {
         return;
     }
@@ -162,7 +183,10 @@ unsafe extern "C" fn animation_get_size<T: PixbufAnimationImpl>(
 
 unsafe extern "C" fn animation_get_static_image<T: PixbufAnimationImpl>(
     ptr: *mut ffi::GdkPixbufAnimation,
-) -> *mut ffi::GdkPixbuf {
+) -> *mut ffi::GdkPixbuf
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimation>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
@@ -192,7 +216,10 @@ unsafe extern "C" fn animation_get_static_image<T: PixbufAnimationImpl>(
 unsafe extern "C" fn animation_get_iter<T: PixbufAnimationImpl>(
     ptr: *mut ffi::GdkPixbufAnimation,
     start_time_ptr: *const glib::ffi::GTimeVal,
-) -> *mut ffi::GdkPixbufAnimationIter {
+) -> *mut ffi::GdkPixbufAnimationIter
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimation>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
diff --git a/gdk-pixbuf/src/subclass/pixbuf_animation_iter.rs b/gdk-pixbuf/src/subclass/pixbuf_animation_iter.rs
index 99d05ccae3ae..4b97b5098e6d 100644
--- a/gdk-pixbuf/src/subclass/pixbuf_animation_iter.rs
+++ b/gdk-pixbuf/src/subclass/pixbuf_animation_iter.rs
@@ -12,7 +12,10 @@ use glib::{prelude::*, subclass::prelude::*, translate::*};
 
 use crate::{ffi, Pixbuf, PixbufAnimationIter};
 
-pub trait PixbufAnimationIterImpl: ObjectImpl {
+pub trait PixbufAnimationIterImpl: ObjectImpl
+where
+    <Self as ObjectSubclass>::Type: IsA<PixbufAnimationIter>,
+{
     // rustdoc-stripper-ignore-next
     /// Time in milliseconds, returning `None` implies showing the same pixbuf forever.
     fn delay_time(&self) -> Option<Duration> {
@@ -33,11 +36,18 @@ pub trait PixbufAnimationIterImpl: ObjectImpl {
 }
 
 mod sealed {
+    use glib::{prelude::*, subclass::prelude::*};
     pub trait Sealed {}
-    impl<T: super::PixbufAnimationIterImplExt> Sealed for T {}
+    impl<T: super::PixbufAnimationIterImplExt> Sealed for T where
+        <T as ObjectSubclass>::Type: IsA<super::PixbufAnimationIter>
+    {
+    }
 }
 
-pub trait PixbufAnimationIterImplExt: sealed::Sealed + ObjectSubclass {
+pub trait PixbufAnimationIterImplExt: sealed::Sealed + ObjectSubclass
+where
+    <Self as ObjectSubclass>::Type: IsA<PixbufAnimationIter>,
+{
     fn parent_delay_time(&self) -> Option<Duration> {
         unsafe {
             let data = Self::type_data();
@@ -121,9 +131,15 @@ pub trait PixbufAnimationIterImplExt: sealed::Sealed + ObjectSubclass {
     }
 }
 
-impl<T: PixbufAnimationIterImpl> PixbufAnimationIterImplExt for T {}
+impl<T: PixbufAnimationIterImpl> PixbufAnimationIterImplExt for T where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimationIter>
+{
+}
 
-unsafe impl<T: PixbufAnimationIterImpl> IsSubclassable<T> for PixbufAnimationIter {
+unsafe impl<T: PixbufAnimationIterImpl> IsSubclassable<T> for PixbufAnimationIter
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimationIter>,
+{
     fn class_init(class: &mut ::glib::Class<Self>) {
         Self::parent_class_init::<T>(class);
 
@@ -137,7 +153,10 @@ unsafe impl<T: PixbufAnimationIterImpl> IsSubclassable<T> for PixbufAnimationIte
 
 unsafe extern "C" fn animation_iter_get_delay_time<T: PixbufAnimationIterImpl>(
     ptr: *mut ffi::GdkPixbufAnimationIter,
-) -> i32 {
+) -> i32
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimationIter>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
@@ -146,7 +165,10 @@ unsafe extern "C" fn animation_iter_get_delay_time<T: PixbufAnimationIterImpl>(
 
 unsafe extern "C" fn animation_iter_get_pixbuf<T: PixbufAnimationIterImpl>(
     ptr: *mut ffi::GdkPixbufAnimationIter,
-) -> *mut ffi::GdkPixbuf {
+) -> *mut ffi::GdkPixbuf
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimationIter>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
@@ -162,7 +184,10 @@ unsafe extern "C" fn animation_iter_get_pixbuf<T: PixbufAnimationIterImpl>(
 
 unsafe extern "C" fn animation_iter_on_currently_loading_frame<T: PixbufAnimationIterImpl>(
     ptr: *mut ffi::GdkPixbufAnimationIter,
-) -> glib::ffi::gboolean {
+) -> glib::ffi::gboolean
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimationIter>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
@@ -172,7 +197,10 @@ unsafe extern "C" fn animation_iter_on_currently_loading_frame<T: PixbufAnimatio
 unsafe extern "C" fn animation_iter_advance<T: PixbufAnimationIterImpl>(
     ptr: *mut ffi::GdkPixbufAnimationIter,
     current_time_ptr: *const glib::ffi::GTimeVal,
-) -> glib::ffi::gboolean {
+) -> glib::ffi::gboolean
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufAnimationIter>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
diff --git a/gdk-pixbuf/src/subclass/pixbuf_loader.rs b/gdk-pixbuf/src/subclass/pixbuf_loader.rs
index c2d53a7132f5..01d152cb33f8 100644
--- a/gdk-pixbuf/src/subclass/pixbuf_loader.rs
+++ b/gdk-pixbuf/src/subclass/pixbuf_loader.rs
@@ -7,7 +7,10 @@ use glib::{prelude::*, subclass::prelude::*, translate::*};
 
 use crate::{ffi, PixbufLoader};
 
-pub trait PixbufLoaderImpl: ObjectImpl {
+pub trait PixbufLoaderImpl: ObjectImpl
+where
+    <Self as ObjectSubclass>::Type: IsA<PixbufLoader>,
+{
     fn size_prepared(&self, width: i32, height: i32) {
         self.parent_size_prepared(width, height)
     }
@@ -26,11 +29,18 @@ pub trait PixbufLoaderImpl: ObjectImpl {
 }
 
 mod sealed {
+    use glib::{prelude::*, subclass::prelude::*};
     pub trait Sealed {}
-    impl<T: super::PixbufLoaderImplExt> Sealed for T {}
+    impl<T: super::PixbufLoaderImplExt> Sealed for T where
+        <Self as ObjectSubclass>::Type: IsA<super::PixbufLoader>
+    {
+    }
 }
 
-pub trait PixbufLoaderImplExt: sealed::Sealed + ObjectSubclass {
+pub trait PixbufLoaderImplExt: sealed::Sealed + ObjectSubclass
+where
+    <Self as ObjectSubclass>::Type: IsA<PixbufLoader>,
+{
     fn parent_size_prepared(&self, width: i32, height: i32) {
         unsafe {
             let data = Self::type_data();
@@ -96,9 +106,15 @@ pub trait PixbufLoaderImplExt: sealed::Sealed + ObjectSubclass {
     }
 }
 
-impl<T: PixbufLoaderImpl> PixbufLoaderImplExt for T {}
+impl<T: PixbufLoaderImpl> PixbufLoaderImplExt for T where
+    <T as ObjectSubclass>::Type: IsA<PixbufLoader>
+{
+}
 
-unsafe impl<T: PixbufLoaderImpl> IsSubclassable<T> for PixbufLoader {
+unsafe impl<T: PixbufLoaderImpl> IsSubclassable<T> for PixbufLoader
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufLoader>,
+{
     fn class_init(class: &mut ::glib::Class<Self>) {
         Self::parent_class_init::<T>(class);
 
@@ -114,14 +130,19 @@ unsafe extern "C" fn loader_size_prepared<T: PixbufLoaderImpl>(
     ptr: *mut ffi::GdkPixbufLoader,
     width: i32,
     height: i32,
-) {
+) where
+    <T as ObjectSubclass>::Type: IsA<PixbufLoader>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
     imp.size_prepared(width, height)
 }
 
-unsafe extern "C" fn loader_area_prepared<T: PixbufLoaderImpl>(ptr: *mut ffi::GdkPixbufLoader) {
+unsafe extern "C" fn loader_area_prepared<T: PixbufLoaderImpl>(ptr: *mut ffi::GdkPixbufLoader)
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufLoader>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
@@ -134,14 +155,19 @@ unsafe extern "C" fn loader_area_updated<T: PixbufLoaderImpl>(
     y: i32,
     width: i32,
     height: i32,
-) {
+) where
+    <T as ObjectSubclass>::Type: IsA<PixbufLoader>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
     imp.area_updated(x, y, width, height)
 }
 
-unsafe extern "C" fn loader_closed<T: PixbufLoaderImpl>(ptr: *mut ffi::GdkPixbufLoader) {
+unsafe extern "C" fn loader_closed<T: PixbufLoaderImpl>(ptr: *mut ffi::GdkPixbufLoader)
+where
+    <T as ObjectSubclass>::Type: IsA<PixbufLoader>,
+{
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();