diff --git a/libavcodec/atrac3.c b/libavcodec/atrac3.c
index faa3daa9e6..fe156fa482 100644
--- a/libavcodec/atrac3.c
+++ b/libavcodec/atrac3.c
@@ -526,7 +526,7 @@ static void reverse_matrixing(float *su1, float *su2, int *prev_code,
             }
             break;
         default:
-            av_assert1(0);
+            av_unreachable("curr_code/matrix_coeff_index_* values are stored in two bits");
         }
     }
 }