diff --git a/gerber/render/cairo_backend.py b/gerber/render/cairo_backend.py
index 7063808..a3ee3fa 100644
--- a/gerber/render/cairo_backend.py
+++ b/gerber/render/cairo_backend.py
@@ -13,12 +13,13 @@
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
-# limitations under the License.
+# limitations under the License.
 
 try:
     import cairo
 except ImportError:
-    import cairocffi as cairo
+    import cairocffi as cairo
+    
 from operator import mul, div
 import math
 import tempfile
@@ -47,7 +48,7 @@ class GerberCairoContext(GerberContext):
     def set_bounds(self, bounds, new_surface=False):
         origin_in_inch = (bounds[0][0], bounds[1][0])
         size_in_inch = (abs(bounds[0][1] - bounds[0][0]), abs(bounds[1][1] - bounds[1][0]))
-        size_in_pixels = map(mul, size_in_inch, self.scale)
+        size_in_pixels = tuple(map(mul, size_in_inch, self.scale))
         self.origin_in_inch = origin_in_inch if self.origin_in_inch is None else self.origin_in_inch
         self.size_in_inch = size_in_inch if self.size_in_inch is None else self.size_in_inch
         if (self.surface is None) or new_surface: