diff --git a/libswresample/swresample_internal.h b/libswresample/swresample_internal.h
index 4c6cf6764e..3137be62da 100644
--- a/libswresample/swresample_internal.h
+++ b/libswresample/swresample_internal.h
@@ -33,7 +33,7 @@ typedef struct AudioData{
 } AudioData;
 
 typedef struct SwrContext {          //FIXME find unused fields
-    AVClass *av_class;
+    const AVClass *av_class;
     int log_level_offset;
     void *log_ctx;
     enum AVSampleFormat  in_sample_fmt;