diff --git a/libavcodec/dvdsub.c b/libavcodec/dvdsub.c
index 2ed015a99a..9a0dd7756d 100644
--- a/libavcodec/dvdsub.c
+++ b/libavcodec/dvdsub.c
@@ -22,9 +22,6 @@
 
 //#define DEBUG
 
-typedef struct DVDSubContext {
-} DVDSubContext;
-
 static int dvdsub_init_decoder(AVCodecContext *avctx)
 {
     return 0;
@@ -412,7 +409,7 @@ AVCodec dvdsub_decoder = {
     "dvdsub",
     CODEC_TYPE_SUBTITLE,
     CODEC_ID_DVD_SUBTITLE,
-    sizeof(DVDSubContext),
+    0,
     dvdsub_init_decoder,
     NULL,
     dvdsub_close_decoder,
diff --git a/libavcodec/dvdsubenc.c b/libavcodec/dvdsubenc.c
index b7224a4f6e..fac29acc2c 100644
--- a/libavcodec/dvdsubenc.c
+++ b/libavcodec/dvdsubenc.c
@@ -23,9 +23,6 @@
 #undef NDEBUG
 #include <assert.h>
 
-typedef struct DVDSubtitleContext {
-} DVDSubtitleContext;
-
 // ncnt is the nibble counter
 #define PUTNIBBLE(val)\
 do {\
@@ -239,7 +236,7 @@ AVCodec dvdsub_encoder = {
     "dvdsub",
     CODEC_TYPE_SUBTITLE,
     CODEC_ID_DVD_SUBTITLE,
-    sizeof(DVDSubtitleContext),
+    0,
     dvdsub_init_encoder,
     dvdsub_encode,
     dvdsub_close_encoder,
diff --git a/libavcodec/ws-snd1.c b/libavcodec/ws-snd1.c
index 2d1ed92b92..eb4fe81d3f 100644
--- a/libavcodec/ws-snd1.c
+++ b/libavcodec/ws-snd1.c
@@ -29,9 +29,6 @@
  * http://www.multimedia.cx
  */
 
-typedef struct {
-} WSSNDContext;
-
 static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};
 static const char ws_adpcm_4bit[] = {
     -9, -8, -6, -5, -4, -3, -2, -1,
@@ -139,7 +136,7 @@ AVCodec ws_snd1_decoder = {
     "ws_snd1",
     CODEC_TYPE_AUDIO,
     CODEC_ID_WESTWOOD_SND1,
-    sizeof(WSSNDContext),
+    0,
     ws_snd_decode_init,
     NULL,
     NULL,