diff --git a/scripts/postprocessing_upscale.py b/scripts/postprocessing_upscale.py
index 9628c4e9a31..2409fd2073e 100644
--- a/scripts/postprocessing_upscale.py
+++ b/scripts/postprocessing_upscale.py
@@ -45,7 +45,7 @@ def ui(self):
                             with gr.Column(scale=4):
                                 upscaling_resize = gr.Slider(minimum=1.0, maximum=8.0, step=0.05, label="Resize", value=4, elem_id="extras_upscaling_resize")
                             with gr.Column(scale=1, min_width=160):
-                                max_side_length = gr.Number(label="Max side length", value=0, elem_id="extras_upscale_max_side_length", tooltip="If any of two sides of the image ends up larger than specified, will downscale it to fit. 0 = no limit.", min_width=160)
+                                max_side_length = gr.Number(label="Max side length", value=0, elem_id="extras_upscale_max_side_length", tooltip="If any of two sides of the image ends up larger than specified, will downscale it to fit. 0 = no limit.", min_width=160, step=8, minimum=0)
 
                     with gr.TabItem('Scale to', elem_id="extras_scale_to_tab") as tab_scale_to:
                         with FormRow():
@@ -154,6 +154,8 @@ def process(self, pp: scripts_postprocessing.PostprocessedImage, upscale_enabled
 
         if upscaler2 and upscaler_2_visibility > 0:
             second_upscale = self.upscale(pp.image, pp.info, upscaler2, upscale_mode, upscale_by, max_side_length, upscale_to_width, upscale_to_height, upscale_crop)
+            if upscaled_image.mode != second_upscale.mode:
+                second_upscale = second_upscale.convert(upscaled_image.mode)
             upscaled_image = Image.blend(upscaled_image, second_upscale, upscaler_2_visibility)
 
             pp.info["Postprocess upscaler 2"] = upscaler2.name