diff --git a/lib/sp-cell-renderer-percent.h b/lib/sp-cell-renderer-percent.h
index 1c747b26..5a21fdc2 100644
--- a/lib/sp-cell-renderer-percent.h
+++ b/lib/sp-cell-renderer-percent.h
@@ -42,6 +42,8 @@ struct _SpCellRendererPercent
 struct _SpCellRendererPercentClass
 {
   GtkCellRendererTextClass parent_class;
+
+  gpointer padding[4];
 };
 
 GType            sp_cell_renderer_percent_get_type    (void);
diff --git a/lib/sp-empty-state-view.h b/lib/sp-empty-state-view.h
index d9f79bbf..4e16e3e5 100644
--- a/lib/sp-empty-state-view.h
+++ b/lib/sp-empty-state-view.h
@@ -30,6 +30,8 @@ G_DECLARE_DERIVABLE_TYPE (SpEmptyStateView, sp_empty_state_view, SP, EMPTY_STATE
 struct _SpEmptyStateViewClass
 {
   GtkBinClass parent;
+
+  gpointer padding[4];
 };
 
 GtkWidget *sp_empty_state_view_new (void);
diff --git a/lib/sp-failed-state-view.h b/lib/sp-failed-state-view.h
index af4605b0..43a4c98a 100644
--- a/lib/sp-failed-state-view.h
+++ b/lib/sp-failed-state-view.h
@@ -32,6 +32,8 @@ G_DECLARE_DERIVABLE_TYPE (SpFailedStateView, sp_failed_state_view, SP, FAILED_ST
 struct _SpFailedStateViewClass
 {
   GtkBinClass parent;
+
+  gpointer padding[4];
 };
 
 GtkWidget *sp_failed_state_view_new          (void);
diff --git a/lib/sp-model-filter.h b/lib/sp-model-filter.h
index 1a6038b2..a74a04cd 100644
--- a/lib/sp-model-filter.h
+++ b/lib/sp-model-filter.h
@@ -33,6 +33,8 @@ G_DECLARE_DERIVABLE_TYPE (SpModelFilter, sp_model_filter, SP, MODEL_FILTER, GObj
 struct _SpModelFilterClass
 {
   GObjectClass parent_class;
+
+  gpointer padding[8];
 };
 
 SpModelFilter *sp_model_filter_new             (GListModel        *child_model);
diff --git a/lib/sp-process-model-row.h b/lib/sp-process-model-row.h
index 2d9f1df3..fe290f55 100644
--- a/lib/sp-process-model-row.h
+++ b/lib/sp-process-model-row.h
@@ -32,6 +32,8 @@ G_DECLARE_DERIVABLE_TYPE (SpProcessModelRow, sp_process_model_row, SP, PROCESS_M
 struct _SpProcessModelRowClass
 {
   GtkListBoxRowClass parent;
+
+  gpointer padding[4];
 };
 
 GtkWidget          *sp_process_model_row_new          (SpProcessModelItem *item);
diff --git a/lib/sp-profiler-menu-button.h b/lib/sp-profiler-menu-button.h
index fcce9d9a..64443a55 100644
--- a/lib/sp-profiler-menu-button.h
+++ b/lib/sp-profiler-menu-button.h
@@ -32,6 +32,8 @@ G_DECLARE_DERIVABLE_TYPE (SpProfilerMenuButton, sp_profiler_menu_button, SP, PRO
 struct _SpProfilerMenuButtonClass
 {
   GtkMenuButtonClass parent_class;
+
+  gpointer padding[8];
 };
 
 GtkWidget  *sp_profiler_menu_button_new          (void);
diff --git a/lib/sp-profiler.h b/lib/sp-profiler.h
index 34663ea5..530b6b9a 100644
--- a/lib/sp-profiler.h
+++ b/lib/sp-profiler.h
@@ -54,6 +54,8 @@ struct _SpProfilerClass
    * completion of stopping.
    */
   void (*stopped) (SpProfiler *self);
+
+  gpointer padding[8];
 };
 
 SpProfiler      *sp_profiler_new                       (void);
diff --git a/lib/sp-recording-state-view.h b/lib/sp-recording-state-view.h
index 37b3b82f..ea7baf04 100644
--- a/lib/sp-recording-state-view.h
+++ b/lib/sp-recording-state-view.h
@@ -32,6 +32,8 @@ G_DECLARE_DERIVABLE_TYPE (SpRecordingStateView, sp_recording_state_view, SP, REC
 struct _SpRecordingStateViewClass
 {
   GtkBinClass parent;
+
+  gpointer padding[4];
 };
 
 GtkWidget *sp_recording_state_view_new          (void);