diff --git a/DeepDrftPublic/Interop/audio/Mp3FormatDecoder.ts b/DeepDrftPublic/Interop/audio/Mp3FormatDecoder.ts
index eda1397..cfb484d 100644
--- a/DeepDrftPublic/Interop/audio/Mp3FormatDecoder.ts
+++ b/DeepDrftPublic/Interop/audio/Mp3FormatDecoder.ts
@@ -79,10 +79,14 @@ export class Mp3FormatDecoder implements IFormatDecoder {
 
         if (info.blockAlign > 0) {
             // CBR: align to complete MP3 frames so each segment is independently decodable.
+            // Guard: need at least one full frame; discard sub-frame tail rather than over-reading.
+            if (availableBytes < info.blockAlign) return 0;
+
             const minFrames = Math.ceil(minSize / info.blockAlign);
             const availableFrames = Math.floor(availableBytes / info.blockAlign);
             if (!streamComplete && availableFrames < minFrames) return 0;
             const requestedFrames = Math.floor(Math.min(requestedSize, availableBytes) / info.blockAlign);
+            // Never exceed availableBytes (clamp via requestedFrames which is floor'd from availableBytes).
             return Math.max(streamComplete ? 1 : minFrames, requestedFrames) * info.blockAlign;
         }