diff --git a/crates/cxx-qt-lib/include/core/qmodelindex.h b/crates/cxx-qt-lib/include/core/qmodelindex.h
index 11df7f320..f49b2bd3f 100644
--- a/crates/cxx-qt-lib/include/core/qmodelindex.h
+++ b/crates/cxx-qt-lib/include/core/qmodelindex.h
@@ -9,12 +9,3 @@
 #include <cinttypes>
 
 #include <QtCore/QModelIndex>
-
-namespace rust {
-namespace cxxqtlib1 {
-
-::std::size_t
-qmodelindexInternalId(const QModelIndex& index);
-
-}
-}
\ No newline at end of file
diff --git a/crates/cxx-qt-lib/src/core/qmodelindex.cpp b/crates/cxx-qt-lib/src/core/qmodelindex.cpp
index 75aeb604f..9664d4155 100644
--- a/crates/cxx-qt-lib/src/core/qmodelindex.cpp
+++ b/crates/cxx-qt-lib/src/core/qmodelindex.cpp
@@ -19,16 +19,3 @@ assert_alignment_and_size(QModelIndex, {
 });
 
 static_assert(::std::is_trivially_copyable<QModelIndex>::value);
-
-namespace rust {
-namespace cxxqtlib1 {
-
-::std::size_t
-qmodelindexInternalId(const QModelIndex& index)
-{
-  // TODO: need to add support for quintptr
-  return static_cast<::std::size_t>(index.internalId());
-}
-
-}
-}
diff --git a/crates/cxx-qt-lib/src/core/qmodelindex.rs b/crates/cxx-qt-lib/src/core/qmodelindex.rs
index de029dabc..053098012 100644
--- a/crates/cxx-qt-lib/src/core/qmodelindex.rs
+++ b/crates/cxx-qt-lib/src/core/qmodelindex.rs
@@ -14,6 +14,7 @@ mod ffi {
 
         type QModelIndex = super::QModelIndex;
         type QString = crate::QString;
+        type quintptr = crate::QUIntPtr;
 
         /// Returns the column this model index refers to.
         fn column(self: &QModelIndex) -> i32;
@@ -35,6 +36,9 @@ mod ffi {
         #[rust_name = "sibling_at_row"]
         fn siblingAtRow(self: &QModelIndex, row: i32) -> QModelIndex;
 
+        /// Returns a `quintptr` used by the model to associate the index with the internal data structure.
+        #[rust_name = "internal_id"]
+        fn internalId(self: &QModelIndex) -> quintptr;
         /// Returns a `*mut c_void` pointer used by the model to associate the index with the internal data structure.
         #[rust_name = "internal_pointer_mut"]
         fn internalPointer(self: &QModelIndex) -> *mut c_void;
@@ -54,10 +58,6 @@ mod ffi {
         #[doc(hidden)]
         #[rust_name = "qmodelindex_to_qstring"]
         fn toQString(value: &QModelIndex) -> QString;
-
-        #[doc(hidden)]
-        #[rust_name = "qmodelindex_internal_id"]
-        fn qmodelindexInternalId(index: &QModelIndex) -> usize;
     }
 }
 
@@ -71,15 +71,6 @@ pub struct QModelIndex {
     _m: MaybeUninit<usize>,
 }
 
-impl QModelIndex {
-    /// Returns a `usize` used by the model to associate the index with the internal data structure.
-    //
-    // TODO: need to add support for quintptr
-    pub fn internal_id(&self) -> usize {
-        ffi::qmodelindex_internal_id(self)
-    }
-}
-
 impl Default for QModelIndex {
     /// Creates a new empty model index. This type of model index is used to indicate that the position in the model is invalid.
     fn default() -> Self {
diff --git a/tests/qt_types_standalone/rust/src/qmodelindex.rs b/tests/qt_types_standalone/rust/src/qmodelindex.rs
index 8ed12131c..bb23b4bc2 100644
--- a/tests/qt_types_standalone/rust/src/qmodelindex.rs
+++ b/tests/qt_types_standalone/rust/src/qmodelindex.rs
@@ -10,6 +10,9 @@ mod qmodelindex_cxx {
     unsafe extern "C++" {
         include!("cxx-qt-lib/qmodelindex.h");
         type QModelIndex = cxx_qt_lib::QModelIndex;
+
+        include!("cxx-qt-lib/qtypes.h");
+        type QUIntPtr = cxx_qt_lib::QUIntPtr;
     }
 
     #[namespace = "rust::cxxqtlib1"]
@@ -23,7 +26,7 @@ mod qmodelindex_cxx {
         fn read_qmodelindex(i: &QModelIndex) -> bool;
         fn clone_qmodelindex(i: &QModelIndex) -> QModelIndex;
         fn internal_pointer_qmodelindex(i: &QModelIndex) -> *mut c_void;
-        fn internal_id_qmodelindex(i: &QModelIndex) -> usize;
+        fn internal_id_qmodelindex(i: &QModelIndex) -> QUIntPtr;
     }
 }
 
@@ -43,6 +46,6 @@ fn internal_pointer_qmodelindex(i: &QModelIndex) -> *mut qmodelindex_cxx::c_void
     i.internal_pointer_mut()
 }
 
-fn internal_id_qmodelindex(i: &QModelIndex) -> usize {
+fn internal_id_qmodelindex(i: &QModelIndex) -> cxx_qt_lib::QUIntPtr {
     i.internal_id()
 }