diff --git a/clutter/clutter-deform-effect.c b/clutter/clutter-deform-effect.c
index 9d6a7f3c5..b976d612d 100644
--- a/clutter/clutter-deform-effect.c
+++ b/clutter/clutter-deform-effect.c
@@ -184,7 +184,10 @@ clutter_deform_effect_paint_target (ClutterOffscreenEffect *effect)
       actor = clutter_actor_meta_get_actor (CLUTTER_ACTOR_META (effect));
       opacity = clutter_actor_get_paint_opacity (actor);
 
-      if (!_clutter_offscreen_effect_get_target_size (effect, &width, &height))
+      /* if we don't have a target size, fall back to the actor's
+       * allocation, though wrong it might be
+       */
+      if (!clutter_offscreen_effect_get_target_size (effect, &width, &height))
         clutter_actor_get_size (actor, &width, &height);
 
       for (i = 0; i < priv->y_tiles + 1; i++)
diff --git a/clutter/clutter-offscreen-effect-private.h b/clutter/clutter-offscreen-effect-private.h
index 6a9137bff..a5249dad3 100644
--- a/clutter/clutter-offscreen-effect-private.h
+++ b/clutter/clutter-offscreen-effect-private.h
@@ -5,10 +5,6 @@
 
 G_BEGIN_DECLS
 
-gboolean        _clutter_offscreen_effect_get_target_size       (ClutterOffscreenEffect *effect,
-                                                                 gfloat                 *width,
-                                                                 gfloat                 *height);
-
 G_END_DECLS
 
 #endif /* __CLUTTER_OFFSCREEN_EFFECT_PRIVATE_H__ */
diff --git a/clutter/clutter-offscreen-effect.c b/clutter/clutter-offscreen-effect.c
index 269640847..804a36288 100644
--- a/clutter/clutter-offscreen-effect.c
+++ b/clutter/clutter-offscreen-effect.c
@@ -476,12 +476,34 @@ clutter_offscreen_effect_create_texture (ClutterOffscreenEffect *effect,
                                                                       height);
 }
 
+/**
+ * clutter_offscreen_effect_get_target_size:
+ * @effect: a #ClutterOffscreenEffect
+ * @width: (out): return location for the target width, or %NULL
+ * @height: (out): return location for the target height, or %NULL
+ *
+ * Retrieves the size of the offscreen buffer used by @effect to
+ * paint the actor to which it has been applied.
+ *
+ * This function should only be called by #ClutterOffscreenEffect
+ * implementations, from within the <function>paint_target()</function>
+ * virtual function.
+ *
+ * Return value: %TRUE if the offscreen buffer has a valid size,
+ *   and %FALSE otherwise
+ *
+ * Since: 1.8
+ */
 gboolean
-_clutter_offscreen_effect_get_target_size (ClutterOffscreenEffect *effect,
-                                           gfloat                 *width,
-                                           gfloat                 *height)
+clutter_offscreen_effect_get_target_size (ClutterOffscreenEffect *effect,
+                                          gfloat                 *width,
+                                          gfloat                 *height)
 {
-  ClutterOffscreenEffectPrivate *priv = effect->priv;
+  ClutterOffscreenEffectPrivate *priv;
+
+  g_return_val_if_fail (CLUTTER_IS_OFFSCREEN_EFFECT (effect), FALSE);
+  
+  priv = effect->priv;
 
   if (priv->target == NULL)
     return FALSE;
diff --git a/clutter/clutter-offscreen-effect.h b/clutter/clutter-offscreen-effect.h
index 0f16c9f31..72636ed5c 100644
--- a/clutter/clutter-offscreen-effect.h
+++ b/clutter/clutter-offscreen-effect.h
@@ -93,12 +93,15 @@ struct _ClutterOffscreenEffectClass
 
 GType clutter_offscreen_effect_get_type (void) G_GNUC_CONST;
 
-CoglMaterial *clutter_offscreen_effect_get_target     (ClutterOffscreenEffect *effect);
+CoglMaterial *  clutter_offscreen_effect_get_target             (ClutterOffscreenEffect *effect);
 
-void          clutter_offscreen_effect_paint_target   (ClutterOffscreenEffect *effect);
-CoglHandle    clutter_offscreen_effect_create_texture (ClutterOffscreenEffect *effect,
-                                                       gfloat                  width,
-                                                       gfloat                  height);
+void            clutter_offscreen_effect_paint_target           (ClutterOffscreenEffect *effect);
+CoglHandle      clutter_offscreen_effect_create_texture         (ClutterOffscreenEffect *effect,
+                                                                 gfloat                  width,
+                                                                 gfloat                  height);
+gboolean        clutter_offscreen_effect_get_target_size        (ClutterOffscreenEffect *effect,
+                                                                 gfloat                 *width,
+                                                                 gfloat                 *height);
 
 G_END_DECLS
 
diff --git a/doc/reference/clutter/clutter-sections.txt b/doc/reference/clutter/clutter-sections.txt
index ba95702eb..3bad5941e 100644
--- a/doc/reference/clutter/clutter-sections.txt
+++ b/doc/reference/clutter/clutter-sections.txt
@@ -2486,6 +2486,7 @@ ClutterOffscreenEffectClass
 clutter_offscreen_effect_get_target
 clutter_offscreen_effect_create_texture
 clutter_offscreen_effect_paint_target
+clutter_offscreen_effect_get_target_size
 <SUBSECTION Standard>
 CLUTTER_TYPE_OFFSCREEN_EFFECT
 CLUTTER_OFFSCREEN_EFFECT