diff --git a/libavformat/nut.c b/libavformat/nut.c
index 61c588c05aaa9eddd0059429a3bc10cfcac10734..9a6a41b21f4d8fa1127390b7fe266d87fd7b8a87 100644
--- a/libavformat/nut.c
+++ b/libavformat/nut.c
@@ -47,11 +47,11 @@ int64_t ff_lsb2full(StreamContext *stream, int64_t lsb){
     return  ((lsb - delta)&mask) + delta;
 }
 
-int ff_nut_sp_pos_cmp(Syncpoint *a, Syncpoint *b){
+int ff_nut_sp_pos_cmp(const Syncpoint *a, const Syncpoint *b){
     return ((a->pos - b->pos) >> 32) - ((b->pos - a->pos) >> 32);
 }
 
-int ff_nut_sp_pts_cmp(Syncpoint *a, Syncpoint *b){
+int ff_nut_sp_pts_cmp(const Syncpoint *a, const Syncpoint *b){
     return ((a->ts - b->ts) >> 32) - ((b->ts - a->ts) >> 32);
 }
 
@@ -62,7 +62,7 @@ void ff_nut_add_sp(NUTContext *nut, int64_t pos, int64_t back_ptr, int64_t ts){
     sp->pos= pos;
     sp->back_ptr= back_ptr;
     sp->ts= ts;
-    av_tree_insert(&nut->syncpoints, sp, ff_nut_sp_pos_cmp, &node);
+    av_tree_insert(&nut->syncpoints, sp, (void *) ff_nut_sp_pos_cmp, &node);
     if(node){
         av_free(sp);
         av_free(node);
diff --git a/libavformat/nut.h b/libavformat/nut.h
index 8d9695245c8856d3ff8fdbdcd77a6f1720707f53..ce052dfedf94da95c13fef07b7e34fefbb3b3265 100644
--- a/libavformat/nut.h
+++ b/libavformat/nut.h
@@ -107,8 +107,8 @@ typedef struct {
 
 void ff_nut_reset_ts(NUTContext *nut, AVRational time_base, int64_t val);
 int64_t ff_lsb2full(StreamContext *stream, int64_t lsb);
-int ff_nut_sp_pos_cmp(Syncpoint *a, Syncpoint *b);
-int ff_nut_sp_pts_cmp(Syncpoint *a, Syncpoint *b);
+int ff_nut_sp_pos_cmp(const Syncpoint *a, const Syncpoint *b);
+int ff_nut_sp_pts_cmp(const Syncpoint *a, const Syncpoint *b);
 void ff_nut_add_sp(NUTContext *nut, int64_t pos, int64_t back_ptr, int64_t ts);
 void ff_nut_free_sp(NUTContext *nut);
 
diff --git a/libavformat/nutdec.c b/libavformat/nutdec.c
index 6e0f1fcf9789feff4d4a35ccb4c0303953fcc062..d08683f54ab3466856f0ef088f1f5d62e4042087 100644
--- a/libavformat/nutdec.c
+++ b/libavformat/nutdec.c
@@ -859,7 +859,8 @@ static int read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flag
         pos2= st->index_entries[index].pos;
         ts  = st->index_entries[index].timestamp;
     }else{
-        av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pts_cmp, (void **) next_node);
+        av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pts_cmp,
+                     (void **) next_node);
         av_log(s, AV_LOG_DEBUG, "%"PRIu64"-%"PRIu64" %"PRId64"-%"PRId64"\n", next_node[0]->pos, next_node[1]->pos,
                                                     next_node[0]->ts , next_node[1]->ts);
         pos= av_gen_search(s, -1, dummy.ts, next_node[0]->pos, next_node[1]->pos, next_node[1]->pos,
@@ -868,7 +869,8 @@ static int read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flag
         if(!(flags & AVSEEK_FLAG_BACKWARD)){
             dummy.pos= pos+16;
             next_node[1]= &nopts_sp;
-            av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, (void **) next_node);
+            av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pos_cmp,
+                         (void **) next_node);
             pos2= av_gen_search(s, -2, dummy.pos, next_node[0]->pos     , next_node[1]->pos, next_node[1]->pos,
                                                 next_node[0]->back_ptr, next_node[1]->back_ptr, flags, &ts, nut_read_timestamp);
             if(pos2>=0)
@@ -876,7 +878,8 @@ static int read_seek(AVFormatContext *s, int stream_index, int64_t pts, int flag
             //FIXME dir but I think it does not matter
         }
         dummy.pos= pos;
-        sp= av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, NULL);
+        sp= av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pos_cmp,
+                         NULL);
 
         assert(sp);
         pos2= sp->back_ptr  - 15;
diff --git a/libavformat/nutenc.c b/libavformat/nutenc.c
index e06a85f54fb3565cd2a250c7bb3d1ec8ea4f45e4..84ea29024eb1b02b99cd84ae56cdb22578983481 100644
--- a/libavformat/nutenc.c
+++ b/libavformat/nutenc.c
@@ -677,7 +677,8 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt){
         }
         if(dummy.pos == INT64_MAX)
             dummy.pos= 0;
-        sp= av_tree_find(nut->syncpoints, &dummy, ff_nut_sp_pos_cmp, NULL);
+        sp= av_tree_find(nut->syncpoints, &dummy, (void *) ff_nut_sp_pos_cmp,
+                         NULL);
 
         nut->last_syncpoint_pos= url_ftell(bc);
         ret = url_open_dyn_buf(&dyn_bc);