diff --git a/libavcodec/adpcm.c b/libavcodec/adpcm.c
index 99ea285c68..f4ca273eb5 100644
--- a/libavcodec/adpcm.c
+++ b/libavcodec/adpcm.c
@@ -1636,6 +1636,7 @@ AVCodec name ## _decoder = {                    \
 #define ADPCM_CODEC(id,name,long_name_)         \
     ADPCM_ENCODER(id,name,long_name_) ADPCM_DECODER(id,name,long_name_)
 
+/* Note: Do not forget to add new entries to the Makefile as well. */
 ADPCM_DECODER(CODEC_ID_ADPCM_4XM, adpcm_4xm, "4X Movie ADPCM");
 ADPCM_DECODER(CODEC_ID_ADPCM_CT, adpcm_ct, "Creative Technology ADPCM");
 ADPCM_DECODER(CODEC_ID_ADPCM_EA, adpcm_ea, "Electronic Arts ADPCM");
diff --git a/libavcodec/pcm.c b/libavcodec/pcm.c
index 6e9a755bcf..29779c5ba0 100644
--- a/libavcodec/pcm.c
+++ b/libavcodec/pcm.c
@@ -556,6 +556,7 @@ AVCodec name ## _decoder = {                    \
 #define PCM_CODEC(id, name, long_name_)         \
     PCM_ENCODER(id,name,long_name_) PCM_DECODER(id,name,long_name_)
 
+/* Note: Do not forget to add new entries to the Makefile as well. */
 PCM_CODEC  (CODEC_ID_PCM_ALAW, pcm_alaw, "A-law PCM");
 PCM_CODEC  (CODEC_ID_PCM_DVD, pcm_dvd, "signed 16|20|24-bit big-endian PCM");
 PCM_CODEC  (CODEC_ID_PCM_MULAW, pcm_mulaw, "mu-law PCM");