diff --git a/libavcodec/vp56dsp.h b/libavcodec/vp56dsp.h
index 692fd0c8ac..3981de4015 100644
--- a/libavcodec/vp56dsp.h
+++ b/libavcodec/vp56dsp.h
@@ -30,7 +30,7 @@ typedef struct VP5DSPContext {
 } VP5DSPContext;
 
 typedef struct VP6DSPContext {
-    void (*vp6_filter_diag4)(uint8_t *dst, uint8_t *src, ptrdiff_t stride,
+    void (*vp6_filter_diag4)(uint8_t *dst, const uint8_t *src, ptrdiff_t stride,
                              const int16_t *h_weights,const int16_t *v_weights);
 } VP6DSPContext;
 
diff --git a/libavcodec/vp6dsp.c b/libavcodec/vp6dsp.c
index 76c4983960..bdaa054307 100644
--- a/libavcodec/vp6dsp.c
+++ b/libavcodec/vp6dsp.c
@@ -27,7 +27,7 @@
 #include "vp56dsp.h"
 
 
-static void vp6_filter_diag4_c(uint8_t *dst, uint8_t *src, ptrdiff_t stride,
+static void vp6_filter_diag4_c(uint8_t *dst, const uint8_t *src, ptrdiff_t stride,
                                const int16_t *h_weights, const int16_t *v_weights)
 {
     int x, y;
diff --git a/libavcodec/x86/vp6dsp_init.c b/libavcodec/x86/vp6dsp_init.c
index 07e3becaec..db9a95767e 100644
--- a/libavcodec/x86/vp6dsp_init.c
+++ b/libavcodec/x86/vp6dsp_init.c
@@ -25,7 +25,7 @@
 #include "libavutil/x86/cpu.h"
 #include "libavcodec/vp56dsp.h"
 
-void ff_vp6_filter_diag4_sse2(uint8_t *dst, uint8_t *src, ptrdiff_t stride,
+void ff_vp6_filter_diag4_sse2(uint8_t *dst, const uint8_t *src, ptrdiff_t stride,
                               const int16_t *h_weights,const int16_t *v_weights);
 
 av_cold void ff_vp6dsp_init_x86(VP6DSPContext *c)