diff --git a/doc/examples/encode_audio.c b/doc/examples/encode_audio.c
index 5932521b2c..b788775a56 100644
--- a/doc/examples/encode_audio.c
+++ b/doc/examples/encode_audio.c
@@ -39,7 +39,7 @@
 #include "libavutil/samplefmt.h"
 
 /* check that a given sample format is supported by the encoder */
-static int check_sample_fmt(AVCodec *codec, enum AVSampleFormat sample_fmt)
+static int check_sample_fmt(const AVCodec *codec, enum AVSampleFormat sample_fmt)
 {
     const enum AVSampleFormat *p = codec->sample_fmts;
 
@@ -52,7 +52,7 @@ static int check_sample_fmt(AVCodec *codec, enum AVSampleFormat sample_fmt)
 }
 
 /* just pick the highest supported samplerate */
-static int select_sample_rate(AVCodec *codec)
+static int select_sample_rate(const AVCodec *codec)
 {
     const int *p;
     int best_samplerate = 0;
@@ -69,7 +69,7 @@ static int select_sample_rate(AVCodec *codec)
 }
 
 /* select layout with the highest channel count */
-static int select_channel_layout(AVCodec *codec)
+static int select_channel_layout(const AVCodec *codec)
 {
     const uint64_t *p;
     uint64_t best_ch_layout = 0;
@@ -94,7 +94,7 @@ static int select_channel_layout(AVCodec *codec)
 int main(int argc, char **argv)
 {
     const char *filename;
-    AVCodec *codec;
+    const AVCodec *codec;
     AVCodecContext *c= NULL;
     AVFrame *frame;
     AVPacket pkt;