diff --git a/Tests/images/no_palette_with_background.gif b/Tests/images/no_palette_with_background.gif
new file mode 100644
index 00000000000..e49e5d461aa
Binary files /dev/null and b/Tests/images/no_palette_with_background.gif differ
diff --git a/Tests/test_file_webp.py b/Tests/test_file_webp.py
index 13fbb529142..c69e13a890e 100644
--- a/Tests/test_file_webp.py
+++ b/Tests/test_file_webp.py
@@ -187,6 +187,12 @@ def test_file_pointer_could_be_reused(self):
 
     @skip_unless_feature("webp_anim")
     def test_background_from_gif(self, tmp_path):
+        # Save L mode GIF with background
+        with Image.open("Tests/images/no_palette_with_background.gif") as im:
+            out_webp = str(tmp_path / "temp.webp")
+            im.save(out_webp, save_all=True)
+
+        # Save P mode GIF with background
         with Image.open("Tests/images/chi.gif") as im:
             original_value = im.convert("RGB").getpixel((1, 1))
 
diff --git a/src/PIL/WebPImagePlugin.py b/src/PIL/WebPImagePlugin.py
index 370b44e3a32..7dd3f527211 100644
--- a/src/PIL/WebPImagePlugin.py
+++ b/src/PIL/WebPImagePlugin.py
@@ -190,7 +190,9 @@ def _save_all(im, fp, filename):
             palette = im.getpalette()
             if palette:
                 r, g, b = palette[background * 3 : (background + 1) * 3]
-                background = (r, g, b, 0)
+                background = (r, g, b, 255)
+            else:
+                background = (background, background, background, 255)
 
     duration = im.encoderinfo.get("duration", im.info.get("duration", 0))
     loop = im.encoderinfo.get("loop", 0)