diff --git a/nn_fingerprint.py b/nn_fingerprint.py
index 709020a..340b5d2 100644
--- a/nn_fingerprint.py
+++ b/nn_fingerprint.py
@@ -117,7 +117,7 @@ class NNFingerprint(NNOperator):
             audio = numpy.hstack(frames)
             if len(audio.shape) == 1:
                 audio = audio[None, :]
-            assert len(audio.shape) == 2
+        assert len(audio.shape) == 2
         audio = self.int2float(audio)
 
         if sr != self.params['sample_rate']: