diff --git a/libswscale/swscale.c b/libswscale/swscale.c
index 170baf9b7c..8a9521fc0e 100644
--- a/libswscale/swscale.c
+++ b/libswscale/swscale.c
@@ -3167,6 +3167,10 @@ int sws_scale(SwsContext *c, uint8_t* src[], int srcStride[], int srcSliceY,
         reset_ptr(src2, c->srcFormat);
         reset_ptr(dst2, c->dstFormat);
 
+        /* reset slice direction at end of frame */
+        if (srcSliceY + srcSliceH == c->srcH)
+            c->sliceDir = 0;
+
         return c->swScale(c, src2, srcStride2, srcSliceY, srcSliceH, dst2, dstStride2);
     } else {
         // slices go from bottom to top => we flip the image internally
@@ -3186,6 +3190,10 @@ int sws_scale(SwsContext *c, uint8_t* src[], int srcStride[], int srcSliceY,
         reset_ptr(src2, c->srcFormat);
         reset_ptr(dst2, c->dstFormat);
 
+        /* reset slice direction at end of frame */
+        if (!srcSliceY)
+            c->sliceDir = 0;
+
         return c->swScale(c, src2, srcStride2, c->srcH-srcSliceY-srcSliceH, srcSliceH, dst2, dstStride2);
     }
 }