diff --git a/src/services/background.js b/src/services/background.js
index ea47e8d..ceedc0f 100644
--- a/src/services/background.js
+++ b/src/services/background.js
@@ -77,18 +77,19 @@ export async function removeBackgroundFrames(frameDataUrls, { onProgress } = {})
   const total = frameDataUrls.length;
 
   for (let i = 0; i < total; i++) {
-    const frameNo = i + 1;
-    const src = frameDataUrls[i];
+    const frameIndex = i;
+    const frameNo = frameIndex + 1;
+    const src = frameDataUrls[frameIndex];
 
     onProgress?.({
-      pct: Math.round((i / total) * 100),
+      pct: Math.round((frameIndex / total) * 100),
       text: `preparing frame ${frameNo} of ${total} for background removal...`
     });
 
     const pngFile = await toPngFile(src, `frame-${frameNo}.png`);
 
     onProgress?.({
-      pct: Math.round((i / total) * 100),
+      pct: Math.round((frameIndex / total) * 100),
       text: `removing background from frame ${frameNo} of ${total}...`
     });
 
@@ -98,7 +99,7 @@ export async function removeBackgroundFrames(frameDataUrls, { onProgress } = {})
       progress: (_key, current, stepTotal) => {
         if (!stepTotal) return;
         const inner = current / stepTotal;
-        const pct = Math.round(((i + inner) / total) * 100);
+        const pct = Math.round(((frameIndex + inner) / total) * 100);
         onProgress?.({
           pct,
           text: `removing background from frame ${frameNo} of ${total}...`