diff --git a/apps/worker/video_processing/gpu_direct_pipeline.py b/apps/worker/video_processing/gpu_direct_pipeline.py
index 051d63705..5203f7eff 100644
--- a/apps/worker/video_processing/gpu_direct_pipeline.py
+++ b/apps/worker/video_processing/gpu_direct_pipeline.py
@@ -192,7 +192,7 @@ def build_direct_render(
         pre_labels.append(label)
 
     # 3. concat（全硬切；原生音频丢弃，v=1:a=0）
-    concat_in = "".join(f"[{l}]" for _lbl in pre_labels)
+    concat_in = "".join(f"[{_lbl}]" for _lbl in pre_labels)
     fc.append(f"{concat_in}concat=n={n}:v=1:a=0[vcat]")
     cur = "vcat"
 
@@ -280,7 +280,7 @@ def build_direct_render(
                 f"[{idx}:a]aresample=44100,volume={vol:.2f},aformat=sample_fmts=fltp:channel_layouts=stereo[{alabel}]"
             )
             mix_labels.append(alabel)
-        mix_in = "".join(f"[{l}]" for _lbl in mix_labels)
+        mix_in = "".join(f"[{_lbl}]" for _lbl in mix_labels)
         fc.append(f"{mix_in}amix=inputs={len(mix_labels)}:duration=first:dropout_transition=2,aresample=44100[afinal]")
         maps.extend(["-map", "[afinal]", "-c:a", "aac", "-b:a", "128k"])