diff --git a/libavfilter/vf_unsharp.c b/libavfilter/vf_unsharp.c
index 3542ca3eac..2bc090f26a 100644
--- a/libavfilter/vf_unsharp.c
+++ b/libavfilter/vf_unsharp.c
@@ -70,6 +70,7 @@ static void unsharpen(uint8_t *dst, const uint8_t *src, int dst_stride, int src_
 
     int32_t res;
     int x, y, z;
+    const uint8_t *src2;
 
     if (!fp->amount) {
         if (dst_stride == src_stride)
@@ -84,9 +85,12 @@ static void unsharpen(uint8_t *dst, const uint8_t *src, int dst_stride, int src_
         memset(sc[y], 0, sizeof(sc[y][0]) * (width + 2 * fp->steps_x));
 
     for (y = -fp->steps_y; y < height + fp->steps_y; y++) {
+        if (y < height)
+            src2 = src;
+
         memset(sr, 0, sizeof(sr[0]) * (2 * fp->steps_x - 1));
         for (x = -fp->steps_x; x < width + fp->steps_x; x++) {
-            tmp1 = x <= 0 ? src[0] : x >= width ? src[width-1] : src[x];
+            tmp1 = x <= 0 ? src2[0] : x >= width ? src2[width-1] : src2[x];
             for (z = 0; z < fp->steps_x * 2; z += 2) {
                 tmp2 = sr[z + 0] + tmp1; sr[z + 0] = tmp1;
                 tmp1 = sr[z + 1] + tmp2; sr[z + 1] = tmp2;