diff --git a/Sources/GtkCustomWidgets/gtk_custom_root_widget.c b/Sources/GtkCustomWidgets/gtk_custom_root_widget.c
index 8c7b0ca9a46..30bbd90e294 100644
--- a/Sources/GtkCustomWidgets/gtk_custom_root_widget.c
+++ b/Sources/GtkCustomWidgets/gtk_custom_root_widget.c
@@ -56,7 +56,7 @@ void gtk_custom_root_widget_allocate(
     root_widget->allocated_height = height;
 
     if (root_widget->resize_callback != NULL) {
-        Size size = { .width = width, .height = height };
+        CustomWidgetSize size = { .width = width, .height = height };
         root_widget->resize_callback(root_widget->resize_callback_data, size);
     }
 }
@@ -111,7 +111,7 @@ void gtk_custom_root_widget_preempt_allocated_size(
 
 void gtk_custom_root_widget_set_resize_callback(
     GtkCustomRootWidget *self,
-    void (*callback)(void*, Size),
+    void (*callback)(void*, CustomWidgetSize),
     void *data
 ) {
     self->resize_callback = callback;
diff --git a/Sources/GtkCustomWidgets/include/gtk_custom_root_widget.h b/Sources/GtkCustomWidgets/include/gtk_custom_root_widget.h
index 250ed483999..b4d51a2c514 100644
--- a/Sources/GtkCustomWidgets/include/gtk_custom_root_widget.h
+++ b/Sources/GtkCustomWidgets/include/gtk_custom_root_widget.h
@@ -12,7 +12,7 @@ extern "C" {
 typedef struct {
     gint width;
     gint height;
-} Size;
+} CustomWidgetSize;
 
 typedef struct _GtkCustomRootWidget {
     GtkWidget parent_instance;
@@ -24,7 +24,7 @@ typedef struct _GtkCustomRootWidget {
     gboolean has_been_allocated;
 
     void *resize_callback_data;
-    void (*resize_callback)(void*, Size);
+    void (*resize_callback)(void*, CustomWidgetSize);
 
     GtkWidget *child;
 } GtkCustomRootWidget;
@@ -72,7 +72,7 @@ void gtk_custom_root_widget_preempt_allocated_size(
 
 void gtk_custom_root_widget_set_resize_callback(
     GtkCustomRootWidget *self,
-    void (*callback)(void*, Size),
+    void (*callback)(void*, CustomWidgetSize),
     void *data
 );