diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c
index ed86e61955..390844711e 100644
--- a/libavcodec/ac3enc.c
+++ b/libavcodec/ac3enc.c
@@ -1572,7 +1572,7 @@ static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
 static void output_frame_end(AC3EncodeContext *s)
 {
     const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
-    int frame_size_58, pad_bytes, crc1, crc2, crc_inv;
+    int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
     uint8_t *frame;
 
     frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
@@ -1594,9 +1594,15 @@ static void output_frame_end(AC3EncodeContext *s)
     AV_WB16(frame + 2, crc1);
 
     /* compute crc2 */
-    crc2 = av_bswap16(av_crc(crc_ctx, 0,
-                             frame + frame_size_58,
-                             s->frame_size - frame_size_58 - 2));
+    crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
+                          s->frame_size - frame_size_58 - 3);
+    crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
+    /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
+    if (crc2 == 0x770B) {
+        frame[s->frame_size - 3] ^= 0x1;
+        crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
+    }
+    crc2 = av_bswap16(crc2);
     AV_WB16(frame + s->frame_size - 2, crc2);
 }