diff --git a/libavfilter/vf_edgedetect.c b/libavfilter/vf_edgedetect.c
index 25424dbcce..a5614ea63b 100644
--- a/libavfilter/vf_edgedetect.c
+++ b/libavfilter/vf_edgedetect.c
@@ -216,7 +216,7 @@ static int get_rounded_direction(int gx, int gy)
 
         if (gx < 0)
             gx = -gx, gy = -gy;
-        gy <<= 16;
+        gy *= (1 << 16);
         tanpi8gx  =  27146 * gx;
         tan3pi8gx = 158218 * gx;
         if (gy > -tan3pi8gx && gy < -tanpi8gx)  return DIRECTION_45UP;