diff --git a/lib/matplotlib/backends/backend_gtk3agg.py b/lib/matplotlib/backends/backend_gtk3agg.py
index 1d146db9164f..ef59c26060dd 100644
--- a/lib/matplotlib/backends/backend_gtk3agg.py
+++ b/lib/matplotlib/backends/backend_gtk3agg.py
@@ -1,5 +1,6 @@
 import numpy as np
 
+from .. import cbook
 from . import backend_agg, backend_cairo, backend_gtk3
 from .backend_cairo import cairo
 from .backend_gtk3 import Gtk, _BackendGTK3
@@ -42,7 +43,7 @@ def on_draw_event(self, widget, ctx):
             width = int(bbox.x1) - int(bbox.x0)
             height = int(bbox.y1) - int(bbox.y0)
 
-            buf = backend_cairo._unmultipled_rgba8888_to_premultiplied_argb32(
+            buf = cbook._unmultipled_rgba8888_to_premultiplied_argb32(
                 np.asarray(self.copy_from_bbox(bbox)))
             image = cairo.ImageSurface.create_for_data(
                 buf.ravel().data, cairo.FORMAT_ARGB32, width, height)