diff --git a/libavcodec/vp5.c b/libavcodec/vp5.c
index ef2d326eea..fc8119c2f5 100644
--- a/libavcodec/vp5.c
+++ b/libavcodec/vp5.c
@@ -34,7 +34,7 @@
 #include "vp5data.h"
 
 
-static int vp5_parse_header(vp56_context_t *s, uint8_t *buf, int buf_size,
+static int vp5_parse_header(vp56_context_t *s, const uint8_t *buf, int buf_size,
                             int *golden_frame)
 {
     vp56_range_coder_t *c = &s->c;
diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
index 8b2a61a9e2..ca6ae76f9e 100644
--- a/libavcodec/vp56.c
+++ b/libavcodec/vp56.c
@@ -495,7 +495,7 @@ static int vp56_size_changed(AVCodecContext *avctx)
 }
 
 int vp56_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
-                      uint8_t *buf, int buf_size)
+                      const uint8_t *buf, int buf_size)
 {
     vp56_context_t *s = avctx->priv_data;
     AVFrame *const p = s->framep[VP56_FRAME_CURRENT];
diff --git a/libavcodec/vp56.h b/libavcodec/vp56.h
index 0bfd13a216..f85f947e7e 100644
--- a/libavcodec/vp56.h
+++ b/libavcodec/vp56.h
@@ -43,13 +43,13 @@ typedef void (*vp56_parse_coeff_t)(vp56_context_t *s);
 typedef void (*vp56_default_models_init_t)(vp56_context_t *s);
 typedef void (*vp56_parse_vector_models_t)(vp56_context_t *s);
 typedef void (*vp56_parse_coeff_models_t)(vp56_context_t *s);
-typedef int (*vp56_parse_header_t)(vp56_context_t *s, uint8_t *buf,
+typedef int (*vp56_parse_header_t)(vp56_context_t *s, const uint8_t *buf,
                                    int buf_size, int *golden_frame);
 
 typedef struct {
     int high;
     int bits;
-    uint8_t *buffer;
+    const uint8_t *buffer;
     unsigned long code_word;
 } vp56_range_coder_t;
 
@@ -172,7 +172,7 @@ void vp56_init(AVCodecContext *avctx, int flip, int has_alpha);
 int vp56_free(AVCodecContext *avctx);
 void vp56_init_dequant(vp56_context_t *s, int quantizer);
 int vp56_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
-                      uint8_t *buf, int buf_size);
+                      const uint8_t *buf, int buf_size);
 
 
 /**
@@ -180,7 +180,7 @@ int vp56_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
  */
 
 static inline void vp56_init_range_decoder(vp56_range_coder_t *c,
-                                           uint8_t *buf, int buf_size)
+                                           const uint8_t *buf, int buf_size)
 {
     c->high = 255;
     c->bits = 8;
diff --git a/libavcodec/vp6.c b/libavcodec/vp6.c
index 9f912d36ee..896f06d4c4 100644
--- a/libavcodec/vp6.c
+++ b/libavcodec/vp6.c
@@ -41,7 +41,7 @@
 static void vp6_parse_coeff(vp56_context_t *s);
 static void vp6_parse_coeff_huffman(vp56_context_t *s);
 
-static int vp6_parse_header(vp56_context_t *s, uint8_t *buf, int buf_size,
+static int vp6_parse_header(vp56_context_t *s, const uint8_t *buf, int buf_size,
                             int *golden_frame)
 {
     vp56_range_coder_t *c = &s->c;