@@ -46,7 +46,7 @@ def on_draw_event(self, widget, ctx):
         else:
             bbox_queue = self._bbox_queue
 
-        if HAS_CAIRO_CFFI:
+        if HAS_CAIRO_CFFI and not isinstance(ctx, cairo.Context):
             ctx = cairo.Context._from_pointer(
                 cairo.ffi.cast('cairo_t **',
                                id(ctx) + object.__basicsize__)[0],
 
@@ -10,7 +10,7 @@
 
 class RendererGTK3Cairo(backend_cairo.RendererCairo):
     def set_context(self, ctx):
-        if HAS_CAIRO_CFFI:
+        if HAS_CAIRO_CFFI and not isinstance(ctx, cairo.Context):
             ctx = cairo.Context._from_pointer(
                 cairo.ffi.cast(
                     'cairo_t **',
 
@@ -410,7 +410,7 @@ def deprecate_axes_colorcycle(value):
 validate_stringlist = _listify_validator(six.text_type)
 validate_stringlist.__doc__ = 'return a list'
 
-validate_gi_preference = _listify_validator(ValidateInStrings('backend.gi_preference',
+validate_gi_preference = _listify_validator(ValidateInStrings(
     'backend.gi_preference', ['gi', 'pgi']))
 
 validate_orientation = ValidateInStrings(