diff --git a/libavcodec/vorbis.c b/libavcodec/vorbis.c
index 28176f3..f80b3ca 100644
--- a/libavcodec/vorbis.c
+++ b/libavcodec/vorbis.c
@@ -179,12 +179,14 @@ static inline void render_line_unrolled(intptr_t x, uint8_t y, int x1,
     }
 }

-static void render_line(int x0, uint8_t y0, int x1, int y1, float *buf)
+static int render_line(int x0, uint8_t y0, int x1, int y1, float *buf)
 {
     int dy  = y1 - y0;
     int adx = x1 - x0;
     int ady = FFABS(dy);
     int sy  = dy < 0 ? -1 : 1;
+    if (adx == 0)
+               return -1;
     buf[x0] = ff_vorbis_floor1_inverse_db_table[y0];
     if (ady*2 <= adx) { // optimized common case
         render_line_unrolled(x0, y0, x1, sy, ady, adx, buf);
@@ -204,6 +206,7 @@ static void render_line(int x0, uint8_t y0, int x1, int y1, float *buf)
             buf[x] = ff_vorbis_floor1_inverse_db_table[y];
         }
     }
+       return 1;
 }

 void ff_vorbis_floor1_render_list(vorbis_floor1_entry * list, int values,