diff --git a/src/core/gcal-event-attendee.c b/src/core/gcal-event-attendee.c
index 2b8c4be4..bf418dbd 100644
--- a/src/core/gcal-event-attendee.c
+++ b/src/core/gcal-event-attendee.c
@@ -202,9 +202,7 @@ gcal_event_attendee_get_property (GObject *object,
 static void
 gcal_event_attendee_dispose (GObject *instance)
 {
-  GcalEventAttendee *self = NULL;
-
-  g_return_if_fail ((self = GCAL_EVENT_ATTENDEE (instance)));
+  GcalEventAttendee *self = GCAL_EVENT_ATTENDEE (instance);
 
   g_clear_pointer (&self->ecal_attendee, e_cal_component_attendee_free);
 }
@@ -360,7 +358,7 @@ gcal_event_attendee_init (GcalEventAttendee *self)
 GcalEventAttendee *
 gcal_event_attendee_new (ECalComponentAttendee *ecal_attendee)
 {
-  g_return_val_if_fail (ecal_attendee != NULL, NULL);
+  g_assert (ecal_attendee != NULL);
 
   GcalEventAttendee *instance = g_object_new (GCAL_TYPE_EVENT_ATTENDEE,
                                               NULL);
@@ -379,7 +377,7 @@ gcal_event_attendee_new (ECalComponentAttendee *ecal_attendee)
 const gchar *
 gcal_event_attendee_get_name (GcalEventAttendee *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), NULL);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   return e_cal_component_attendee_get_cn (self->ecal_attendee);
 }
@@ -395,7 +393,7 @@ gcal_event_attendee_get_attendee_type (GcalEventAttendee *self)
 {
   ICalParameterCutype ical_type;
 
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), GCAL_EVENT_ATTENDEE_TYPE_NONE);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   ical_type = e_cal_component_attendee_get_cutype (self->ecal_attendee);
 
@@ -411,7 +409,7 @@ gcal_event_attendee_get_attendee_type (GcalEventAttendee *self)
 const gchar *
 gcal_event_attendee_get_delegated_from (GcalEventAttendee *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), NULL);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   return e_cal_component_attendee_get_delegatedfrom (self->ecal_attendee);
 }
@@ -425,7 +423,7 @@ gcal_event_attendee_get_delegated_from (GcalEventAttendee *self)
 const gchar *
 gcal_event_attendee_get_delegated_to (GcalEventAttendee *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), NULL);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   return e_cal_component_attendee_get_delegatedto (self->ecal_attendee);
 }
@@ -439,7 +437,7 @@ gcal_event_attendee_get_delegated_to (GcalEventAttendee *self)
 const gchar *
 gcal_event_attendee_get_language (GcalEventAttendee *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), NULL);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   return e_cal_component_attendee_get_language (self->ecal_attendee);
 }
@@ -453,7 +451,7 @@ gcal_event_attendee_get_language (GcalEventAttendee *self)
 const gchar *
 gcal_event_attendee_get_member (GcalEventAttendee *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), NULL);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   return e_cal_component_attendee_get_member (self->ecal_attendee);
 }
@@ -471,7 +469,7 @@ gcal_event_attendee_get_part_status (GcalEventAttendee *self)
 {
   ICalParameterPartstat ical_partstat;
 
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), GCAL_EVENT_ATTENDEE_PART_NONE);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   ical_partstat = e_cal_component_attendee_get_partstat (self->ecal_attendee);
 
@@ -493,7 +491,7 @@ gcal_event_attendee_get_role (GcalEventAttendee *self)
 {
   ICalParameterRole ical_role;
 
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), GCAL_EVENT_ATTENDEE_ROLE_NONE);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   ical_role = e_cal_component_attendee_get_role (self->ecal_attendee);
 
@@ -509,7 +507,7 @@ gcal_event_attendee_get_role (GcalEventAttendee *self)
 gboolean
 gcal_event_attendee_get_requires_rsvp (GcalEventAttendee *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), FALSE);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   return e_cal_component_attendee_get_rsvp (self->ecal_attendee);
 }
@@ -523,7 +521,7 @@ gcal_event_attendee_get_requires_rsvp (GcalEventAttendee *self)
 const gchar *
 gcal_event_attendee_get_sent_by (GcalEventAttendee *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), NULL);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   return e_cal_component_attendee_get_sentby (self->ecal_attendee);
 }
@@ -541,7 +539,7 @@ gcal_event_attendee_get_sent_by (GcalEventAttendee *self)
 const gchar *
 gcal_event_attendee_get_uri (GcalEventAttendee *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (self), NULL);
+  g_assert (GCAL_IS_EVENT_ATTENDEE (self));
 
   return e_cal_component_attendee_get_value (self->ecal_attendee);
 }
diff --git a/src/core/gcal-event-organizer.c b/src/core/gcal-event-organizer.c
index a7db468e..cdba0e9b 100644
--- a/src/core/gcal-event-organizer.c
+++ b/src/core/gcal-event-organizer.c
@@ -152,7 +152,7 @@ gcal_event_organizer_new (ECalComponentOrganizer *ecal_organizer)
 {
   g_autoptr (GcalEventOrganizer) self = NULL;
 
-  g_return_val_if_fail (ecal_organizer != NULL, NULL);
+  g_assert (ecal_organizer != NULL);
 
   self = g_object_new (GCAL_TYPE_EVENT_ORGANIZER, NULL);
   self->ecal_organizer = e_cal_component_organizer_copy (ecal_organizer);
@@ -169,7 +169,7 @@ gcal_event_organizer_new (ECalComponentOrganizer *ecal_organizer)
 const gchar *
 gcal_event_organizer_get_name (GcalEventOrganizer *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ORGANIZER (self), NULL);
+  g_assert (GCAL_IS_EVENT_ORGANIZER (self));
 
   return e_cal_component_organizer_get_cn (self->ecal_organizer);
 }
@@ -186,7 +186,7 @@ gcal_event_organizer_get_name (GcalEventOrganizer *self)
 const gchar *
 gcal_event_organizer_get_uri (GcalEventOrganizer *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ORGANIZER (self), NULL);
+  g_assert (GCAL_IS_EVENT_ORGANIZER (self));
 
   return e_cal_component_organizer_get_value (self->ecal_organizer);
 }
@@ -200,7 +200,7 @@ gcal_event_organizer_get_uri (GcalEventOrganizer *self)
 const gchar *
 gcal_event_organizer_get_sent_by (GcalEventOrganizer *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ORGANIZER (self), NULL);
+  g_assert (GCAL_IS_EVENT_ORGANIZER (self));
 
   return e_cal_component_organizer_get_sentby (self->ecal_organizer);
 }
@@ -214,7 +214,7 @@ gcal_event_organizer_get_sent_by (GcalEventOrganizer *self)
 const gchar *
 gcal_event_organizer_get_language (GcalEventOrganizer *self)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ORGANIZER (self), NULL);
+  g_assert (GCAL_IS_EVENT_ORGANIZER (self));
 
   return e_cal_component_organizer_get_language (self->ecal_organizer);
 }
diff --git a/src/gui/event-editor/gcal-attendee-details-page.c b/src/gui/event-editor/gcal-attendee-details-page.c
index effbce3b..0d38bae6 100644
--- a/src/gui/event-editor/gcal-attendee-details-page.c
+++ b/src/gui/event-editor/gcal-attendee-details-page.c
@@ -70,7 +70,7 @@ G_DEFINE_FINAL_TYPE (GcalAttendeeDetailsPage, gcal_attendee_details_page, ADW_TY
 static void
 gcal_attendee_details_page_clear_list (GcalAttendeeDetailsPage *self)
 {
-  g_return_if_fail (GCAL_IS_ATTENDEE_DETAILS_PAGE (self));
+  g_assert (GCAL_IS_ATTENDEE_DETAILS_PAGE (self));
 
   g_list_store_remove_all (self->attendees);
 }
@@ -212,7 +212,7 @@ gcal_attendee_details_page_get_property (GObject    *object,
 static void
 gcal_attendee_details_page_init (GcalAttendeeDetailsPage *instance)
 {
-  g_return_if_fail (GCAL_IS_ATTENDEE_DETAILS_PAGE (instance));
+  g_assert (GCAL_IS_ATTENDEE_DETAILS_PAGE (instance));
 
   instance->attendees = g_list_store_new (GCAL_TYPE_EVENT_ATTENDEE);
   gcal_attendee_details_page_init_filters (instance);
@@ -330,7 +330,7 @@ void
 gcal_attendee_details_page_set_event (GcalAttendeeDetailsPage *self,
                                       GcalEvent               *event)
 {
-  g_return_if_fail (GCAL_IS_ATTENDEE_DETAILS_PAGE (self));
+  g_assert (GCAL_IS_ATTENDEE_DETAILS_PAGE (self));
 
   if (self->event == event)
     return;
diff --git a/src/gui/event-editor/gcal-attendee-row.c b/src/gui/event-editor/gcal-attendee-row.c
index 6b76a665..8e3dc291 100644
--- a/src/gui/event-editor/gcal-attendee-row.c
+++ b/src/gui/event-editor/gcal-attendee-row.c
@@ -75,7 +75,7 @@ show_context_menu (GcalAttendeeRow *self,
                    double           x,
                    double           y)
 {
-  g_return_if_fail (GCAL_IS_ATTENDEE_ROW (self));
+  g_assert (GCAL_IS_ATTENDEE_ROW (self));
 
   const GdkRectangle position = { .x = x, .y = y };
   gtk_popover_set_pointing_to (GTK_POPOVER (self->context_menu), &position);
@@ -254,8 +254,6 @@ gcal_attendee_row_init (GcalAttendeeRow *instance)
 GtkWidget *
 gcal_attendee_row_new (GcalEventAttendee *attendee)
 {
-  g_return_val_if_fail (GCAL_IS_EVENT_ATTENDEE (attendee), NULL);
-
   return g_object_new (GCAL_TYPE_ATTENDEE_ROW,
                        "attendee", attendee,
                        NULL);
@@ -272,7 +270,7 @@ gcal_attendee_row_new (GcalEventAttendee *attendee)
 GcalEventAttendee *
 gcal_attendee_row_get_attendee (GcalAttendeeRow *self)
 {
-  g_return_val_if_fail (GCAL_IS_ATTENDEE_ROW (self), NULL);
+  g_assert (GCAL_IS_ATTENDEE_ROW (self));
 
   return self->attendee;
 }
diff --git a/src/gui/event-editor/gcal-attendees-section.c b/src/gui/event-editor/gcal-attendees-section.c
index f955d55d..a1e02e31 100644
--- a/src/gui/event-editor/gcal-attendees-section.c
+++ b/src/gui/event-editor/gcal-attendees-section.c
@@ -214,7 +214,7 @@ gcal_event_editor_section_init_iface (GcalEventEditorSectionInterface *iface)
 static guint
 gcal_attendees_section_get_num_participants (GcalAttendeesSection *self)
 {
-  g_return_val_if_fail (GCAL_IS_ATTENDEES_SECTION (self), 0);
+  g_assert (GCAL_IS_ATTENDEES_SECTION (self));
 
   return self->num_accepted + self->num_declined + self->num_tentative + self->num_delegated + self->num_not_responded;
 }
diff --git a/src/gui/event-editor/gcal-event-editor-dialog.c b/src/gui/event-editor/gcal-event-editor-dialog.c
index 8137b4b6..0ce0c951 100644
--- a/src/gui/event-editor/gcal-event-editor-dialog.c
+++ b/src/gui/event-editor/gcal-event-editor-dialog.c
@@ -313,7 +313,7 @@ static void
 on_attendees_summary_activated_cb (GcalAttendeesSection  *section,
                                    GcalEventEditorDialog *self)
 {
-  g_return_if_fail (GCAL_IS_EVENT_EDITOR_DIALOG (self));
+  g_assert (GCAL_IS_EVENT_EDITOR_DIALOG (self));
 
   gcal_attendee_details_page_set_event (GCAL_ATTENDEE_DETAILS_PAGE (self->attendee_details_page),
                                         self->event);