diff --git a/libavformat/xwma.c b/libavformat/xwma.c
index 6e74a338bf..babe9bcd30 100644
--- a/libavformat/xwma.c
+++ b/libavformat/xwma.c
@@ -253,7 +253,7 @@ static int xwma_read_header(AVFormatContext *s)
          * the total duration using the average bits per sample and the
          * total data length.
          */
-        st->duration = (size<<3) * st->codecpar->sample_rate / st->codecpar->bit_rate;
+        st->duration = av_rescale((size<<3), st->codecpar->sample_rate, st->codecpar->bit_rate);
     }
 
 fail: