diff --git a/doc/examples/decoding_encoding.c b/doc/examples/decoding_encoding.c
index cb63294b14..9280b57ad3 100644
--- a/doc/examples/decoding_encoding.c
+++ b/doc/examples/decoding_encoding.c
@@ -29,6 +29,8 @@
  * format handling
  */
 
+#include <math.h>
+
 #include "libavutil/imgutils.h"
 #include "libavutil/opt.h"
 #include "libavcodec/avcodec.h"