diff --git a/libavcodec/motion_est.c b/libavcodec/motion_est.c
index 72184ed560..cabff8b894 100644
--- a/libavcodec/motion_est.c
+++ b/libavcodec/motion_est.c
@@ -52,7 +52,7 @@ static inline int sad_hpel_motion_search(MpegEncContext * s,
                                   int src_index, int ref_index,
                                   int size, int h);
 
-static inline int update_map_generation(MotionEstContext *c)
+static inline unsigned update_map_generation(MotionEstContext *c)
 {
     c->map_generation+= 1<<(ME_MAP_MV_BITS*2);
     if(c->map_generation==0){
diff --git a/libavcodec/motion_est_template.c b/libavcodec/motion_est_template.c
index d65edd933a..d104954aab 100644
--- a/libavcodec/motion_est_template.c
+++ b/libavcodec/motion_est_template.c
@@ -158,8 +158,8 @@ static int hpel_motion_search(MpegEncContext * s,
         const int b= score_map[(index+(1<<ME_MAP_SHIFT))&(ME_MAP_SIZE-1)]
                      + (mv_penalty[bx   - pred_x] + mv_penalty[by+2 - pred_y])*c->penalty_factor;
 
-        int key;
-        int map_generation= c->map_generation;
+        unsigned key;
+        unsigned map_generation= c->map_generation;
 #ifndef NDEBUG
         uint32_t *map= c->map;
 #endif
@@ -278,7 +278,7 @@ static int qpel_motion_search(MpegEncContext * s,
     const int mx = *mx_ptr;
     const int my = *my_ptr;
     const int penalty_factor= c->sub_penalty_factor;
-    const int map_generation= c->map_generation;
+    const unsigned map_generation = c->map_generation;
     const int subpel_quality= c->avctx->me_subpel_quality;
     uint32_t *map= c->map;
     me_cmp_func cmpf, chroma_cmpf;
@@ -495,7 +495,7 @@ static int qpel_motion_search(MpegEncContext * s,
 
 #define CHECK_MV(x,y)\
 {\
-    const int key= ((y)<<ME_MAP_MV_BITS) + (x) + map_generation;\
+    const unsigned key = ((y)<<ME_MAP_MV_BITS) + (x) + map_generation;\
     const int index= (((y)<<ME_MAP_SHIFT) + (x))&(ME_MAP_SIZE-1);\
     assert((x) >= xmin);\
     assert((x) <= xmax);\
@@ -523,7 +523,7 @@ static int qpel_motion_search(MpegEncContext * s,
 
 #define CHECK_MV_DIR(x,y,new_dir)\
 {\
-    const int key= ((y)<<ME_MAP_MV_BITS) + (x) + map_generation;\
+    const unsigned key = ((y)<<ME_MAP_MV_BITS) + (x) + map_generation;\
     const int index= (((y)<<ME_MAP_SHIFT) + (x))&(ME_MAP_SIZE-1);\
 /*printf("check_mv_dir %d %d %d\n", x, y, new_dir);*/\
     if(map[index]!=key){\
@@ -561,13 +561,13 @@ static av_always_inline int small_diamond_search(MpegEncContext * s, int *best,
     int next_dir=-1;
     LOAD_COMMON
     LOAD_COMMON2
-    int map_generation= c->map_generation;
+    unsigned map_generation = c->map_generation;
 
     cmpf= s->dsp.me_cmp[size];
     chroma_cmpf= s->dsp.me_cmp[size+1];
 
     { /* ensure that the best point is in the MAP as h/qpel refinement needs it */
-        const int key= (best[1]<<ME_MAP_MV_BITS) + best[0] + map_generation;
+        const unsigned key = (best[1]<<ME_MAP_MV_BITS) + best[0] + map_generation;
         const int index= ((best[1]<<ME_MAP_SHIFT) + best[0])&(ME_MAP_SIZE-1);
         if(map[index]!=key){ //this will be executed only very rarey
             score_map[index]= cmp(s, best[0], best[1], 0, 0, size, h, ref_index, src_index, cmpf, chroma_cmpf, flags);
@@ -603,7 +603,7 @@ static int funny_diamond_search(MpegEncContext * s, int *best, int dmin,
     int dia_size;
     LOAD_COMMON
     LOAD_COMMON2
-    int map_generation= c->map_generation;
+    unsigned map_generation = c->map_generation;
 
     cmpf= s->dsp.me_cmp[size];
     chroma_cmpf= s->dsp.me_cmp[size+1];
@@ -644,7 +644,7 @@ static int hex_search(MpegEncContext * s, int *best, int dmin,
     me_cmp_func cmpf, chroma_cmpf;
     LOAD_COMMON
     LOAD_COMMON2
-    int map_generation= c->map_generation;
+    unsigned map_generation = c->map_generation;
     int x,y,d;
     const int dec= dia_size & (dia_size-1);
 
@@ -678,7 +678,7 @@ static int l2s_dia_search(MpegEncContext * s, int *best, int dmin,
     me_cmp_func cmpf, chroma_cmpf;
     LOAD_COMMON
     LOAD_COMMON2
-    int map_generation= c->map_generation;
+    unsigned map_generation = c->map_generation;
     int x,y,i,d;
     int dia_size= c->dia_size&0xFF;
     const int dec= dia_size & (dia_size-1);
@@ -716,7 +716,7 @@ static int umh_search(MpegEncContext * s, int *best, int dmin,
     me_cmp_func cmpf, chroma_cmpf;
     LOAD_COMMON
     LOAD_COMMON2
-    int map_generation= c->map_generation;
+    unsigned map_generation = c->map_generation;
     int x,y,x2,y2, i, j, d;
     const int dia_size= c->dia_size&0xFE;
     static const int hex[16][2]={{-4,-2}, {-4,-1}, {-4, 0}, {-4, 1}, {-4, 2},
@@ -763,7 +763,7 @@ static int full_search(MpegEncContext * s, int *best, int dmin,
     me_cmp_func cmpf, chroma_cmpf;
     LOAD_COMMON
     LOAD_COMMON2
-    int map_generation= c->map_generation;
+    unsigned map_generation = c->map_generation;
     int x,y, d;
     const int dia_size= c->dia_size&0xFF;
 
@@ -792,7 +792,7 @@ static int full_search(MpegEncContext * s, int *best, int dmin,
 
 #define SAB_CHECK_MV(ax,ay)\
 {\
-    const int key= ((ay)<<ME_MAP_MV_BITS) + (ax) + map_generation;\
+    const unsigned key = ((ay)<<ME_MAP_MV_BITS) + (ax) + map_generation;\
     const int index= (((ay)<<ME_MAP_SHIFT) + (ax))&(ME_MAP_SIZE-1);\
 /*printf("sab check %d %d\n", ax, ay);*/\
     if(map[index]!=key){\
@@ -831,7 +831,7 @@ static int sab_diamond_search(MpegEncContext * s, int *best, int dmin,
     int i, j;
     LOAD_COMMON
     LOAD_COMMON2
-    int map_generation= c->map_generation;
+    unsigned map_generation = c->map_generation;
 
     cmpf= s->dsp.me_cmp[size];
     chroma_cmpf= s->dsp.me_cmp[size+1];
@@ -916,7 +916,7 @@ static int var_diamond_search(MpegEncContext * s, int *best, int dmin,
     int dia_size;
     LOAD_COMMON
     LOAD_COMMON2
-    int map_generation= c->map_generation;
+    unsigned map_generation = c->map_generation;
 
     cmpf= s->dsp.me_cmp[size];
     chroma_cmpf= s->dsp.me_cmp[size+1];
@@ -1008,7 +1008,7 @@ static av_always_inline int epzs_motion_search_internal(MpegEncContext * s, int
     int d;                   ///< the score (cmp + penalty) of any given mv
     int dmin;                /*!< the best value of d, i.e. the score
                                corresponding to the mv stored in best[]. */
-    int map_generation;
+    unsigned map_generation;
     int penalty_factor;
     const int ref_mv_stride= s->mb_stride; //pass as arg  FIXME
     const int ref_mv_xy= s->mb_x + s->mb_y*ref_mv_stride; //add to last_mv beforepassing FIXME
@@ -1136,7 +1136,7 @@ static int epzs_motion_search4(MpegEncContext * s,
     MotionEstContext * const c= &s->me;
     int best[2]={0, 0};
     int d, dmin;
-    int map_generation;
+    unsigned map_generation;
     const int penalty_factor= c->penalty_factor;
     const int size=1;
     const int h=8;
@@ -1196,7 +1196,7 @@ static int epzs_motion_search2(MpegEncContext * s,
     MotionEstContext * const c= &s->me;
     int best[2]={0, 0};
     int d, dmin;
-    int map_generation;
+    unsigned map_generation;
     const int penalty_factor= c->penalty_factor;
     const int size=0; //FIXME pass as arg
     const int h=8;
diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
index 0fc32b9abe..e7ab58f46b 100644
--- a/libavcodec/mpegvideo.h
+++ b/libavcodec/mpegvideo.h
@@ -153,7 +153,7 @@ typedef struct MotionEstContext{
     int best_bits;
     uint32_t *map;                     ///< map to avoid duplicate evaluations
     uint32_t *score_map;               ///< map to store the scores
-    int map_generation;
+    unsigned map_generation;
     int pre_penalty_factor;
     int penalty_factor;                /*!< an estimate of the bits required to
                                         code a given mv value, e.g. (1,0) takes