diff --git a/frontend/src/Waveform.tsx b/frontend/src/Waveform.tsx
index a421cb5..aa9235e 100644
--- a/frontend/src/Waveform.tsx
+++ b/frontend/src/Waveform.tsx
@@ -109,7 +109,12 @@ export const Waveform: React.FC<Props> = ({
   // helpers
 
   const frameToCanvasX = (frame: number): number => {
-    const pixelsPerFrame = CanvasLogicalWidth / (viewport.end - viewport.start);
+    const numFrames = viewport.end - viewport.start;
+    if (numFrames == 0) {
+      return 0;
+    }
+
+    const pixelsPerFrame = CanvasLogicalWidth / numFrames;
     return Math.round((frame - viewport.start) * pixelsPerFrame);
   };