diff --git a/doc/webp-container-spec.txt b/doc/webp-container-spec.txt
index ffcb1541..53953cae 100644
--- a/doc/webp-container-spec.txt
+++ b/doc/webp-container-spec.txt
@@ -378,6 +378,9 @@ color is also used when disposal method is `1`.
   * Viewer applications SHOULD treat the background color value as a hint, and
     are not required to use it.
 
+  * The canvas is cleared at the start of each loop. The background color MAY be
+    used to achieve this.
+
 Loop Count: 16 bits (_uint16_)
 
 : The number of times to loop the animation. `0` means infinitely.
@@ -719,33 +722,37 @@ pseudocode:
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 assert VP8X.flags.hasAnimation
 canvas ← new image of size VP8X.canvasWidth x VP8X.canvasHeight with
-background color ANIM.background_color.
+         background color ANIM.background_color.
 loop_count ← ANIM.loopCount
 dispose_method ← ANIM.disposeMethod
 if loop_count == 0:
     loop_count = ∞
 frame_params ← nil
-for loop = 0, ..., loop_count - 1
-    assert next chunk in image_data is ANMF
-    frame_params.frameX = Frame X
-    frame_params.frameY = Frame Y
-    frame_params.frameWidth = Frame Width Minus One + 1
-    frame_params.frameHeight = Frame Height Minus One + 1
-    frame_params.frameDuration = Frame Duration
-    assert VP8X.canvasWidth >= frame_params.frameX + frame_params.frameWidth
-    assert VP8X.canvasHeight >= frame_params.frameY + frame_params.frameHeight
-    for subchunk in 'Frame Data':
-        if subchunk.tag == "ALPH":
-            assert alpha subchunks not found in 'Frame Data' earlier
-            frame_params.alpha = alpha_data
-        else if subchunk.tag == "VP8 " OR subchunk.tag == "VP8L":
-            assert bitstream subchunks not found in 'Frame Data' earlier
-            frame_params.bitstream = bitstream_data
-    render frame with frame_params.alpha and frame_params.bitstream on canvas
-    with top-left corner in (frame_params.frameX, frame_params.frameY), using
-    dispose method dispose_method.
-    Show the contents of the image for frame_params.frameDuration * 1ms.
-canvas contains the decoded canvas.
+assert next chunk in image_data is ANMF
+for loop = 0..loop_count - 1
+    clear canvas to ANIM.background_color or application defined color
+    until eof or non-ANMF chunk
+        frame_params.frameX = Frame X
+        frame_params.frameY = Frame Y
+        frame_params.frameWidth = Frame Width Minus One + 1
+        frame_params.frameHeight = Frame Height Minus One + 1
+        frame_params.frameDuration = Frame Duration
+        frame_right = frame_params.frameX + frame_params.frameWidth
+        frame_bottom = frame_params.frameY + frame_params.frameHeight
+        assert VP8X.canvasWidth >= frame_right
+        assert VP8X.canvasHeight >= frame_bottom
+        for subchunk in 'Frame Data':
+            if subchunk.tag == "ALPH":
+                assert alpha subchunks not found in 'Frame Data' earlier
+                frame_params.alpha = alpha_data
+            else if subchunk.tag == "VP8 " OR subchunk.tag == "VP8L":
+                assert bitstream subchunks not found in 'Frame Data' earlier
+                frame_params.bitstream = bitstream_data
+        render frame with frame_params.alpha and frame_params.bitstream on
+            canvas with top-left corner at (frame_params.frameX,
+            frame_params.frameY), using dispose method dispose_method.
+        canvas contains the decoded image.
+        Show the contents of the canvas for frame_params.frameDuration * 1ms.
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
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