diff --git a/libavformat/au.c b/libavformat/au.c
index e4245a1de1..269a508bcc 100644
--- a/libavformat/au.c
+++ b/libavformat/au.c
@@ -100,7 +100,7 @@ static int au_read_header(AVFormatContext *s)
     codec = ff_codec_get_id(codec_au_tags, id);
 
     if (codec == AV_CODEC_ID_NONE) {
-        av_log_ask_for_sample(s, "unknown or unsupported codec tag: %d\n", id);
+        av_log_ask_for_sample(s, "unknown or unsupported codec tag: %u\n", id);
         return AVERROR_PATCHWELCOME;
     }
 
@@ -111,7 +111,12 @@ static int au_read_header(AVFormatContext *s)
     }
 
     if (channels == 0 || channels >= INT_MAX / (BLOCK_SIZE * bps >> 3)) {
-        av_log(s, AV_LOG_ERROR, "Invalid number of channels %d\n", channels);
+        av_log(s, AV_LOG_ERROR, "Invalid number of channels %u\n", channels);
+        return AVERROR_INVALIDDATA;
+    }
+
+    if (rate == 0 || rate > INT_MAX) {
+        av_log(s, AV_LOG_ERROR, "Invalid sample rate: %u\n", rate);
         return AVERROR_INVALIDDATA;
     }