diff --git a/modules/img2img.py b/modules/img2img.py
index ac9fd3f843d..328cb0e9e24 100644
--- a/modules/img2img.py
+++ b/modules/img2img.py
@@ -129,7 +129,7 @@ def img2img(id_task: str, mode: int, prompt: str, negative_prompt: str, prompt_s
         mask = None
     elif mode == 2:  # inpaint
         image, mask = init_img_with_mask["image"], init_img_with_mask["mask"]
-        mask = mask.split()[-1].convert("L").point(lambda x: 255 if x > 128 else 0)
+        mask = processing.create_binary_mask(mask)
         image = image.convert("RGB")
     elif mode == 3:  # inpaint sketch
         image = inpaint_color_sketch
diff --git a/modules/processing.py b/modules/processing.py
index 1d098302ead..e62db62fd9c 100755
--- a/modules/processing.py
+++ b/modules/processing.py
@@ -81,6 +81,12 @@ def apply_overlay(image, paste_loc, index, overlays):
 
     return image
 
+def create_binary_mask(image):
+    if image.mode == 'RGBA' and image.getextrema()[-1] != (255, 255):
+        image = image.split()[-1].convert("L").point(lambda x: 255 if x > 128 else 0)
+    else:
+        image = image.convert('L')
+    return image
 
 def txt2img_image_conditioning(sd_model, x, width, height):
     if sd_model.model.conditioning_key in {'hybrid', 'concat'}: # Inpainting models
@@ -1385,7 +1391,9 @@ def init(self, all_prompts, all_seeds, all_subseeds):
         image_mask = self.image_mask
 
         if image_mask is not None:
-            image_mask = image_mask.convert('L')
+            # image_mask is passed in as RGBA by Gradio to support alpha masks,
+            # but we still want to support binary masks.
+            image_mask = create_binary_mask(image_mask)
 
             if self.inpainting_mask_invert:
                 image_mask = ImageOps.invert(image_mask)
diff --git a/modules/ui.py b/modules/ui.py
index a6b1f964b0a..c98d9849632 100644
--- a/modules/ui.py
+++ b/modules/ui.py
@@ -598,7 +598,7 @@ def update_orig(image, state):
 
                     with gr.TabItem('Inpaint upload', id='inpaint_upload', elem_id="img2img_inpaint_upload_tab") as tab_inpaint_upload:
                         init_img_inpaint = gr.Image(label="Image for img2img", show_label=False, source="upload", interactive=True, type="pil", elem_id="img_inpaint_base")
-                        init_mask_inpaint = gr.Image(label="Mask", source="upload", interactive=True, type="pil", elem_id="img_inpaint_mask")
+                        init_mask_inpaint = gr.Image(label="Mask", source="upload", interactive=True, type="pil", image_mode="RGBA", elem_id="img_inpaint_mask")
 
                     with gr.TabItem('Batch', id='batch', elem_id="img2img_batch_tab") as tab_batch:
                         hidden = '<br>Disabled when launched with --hide-ui-dir-config.' if shared.cmd_opts.hide_ui_dir_config else ''