diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c
index 836b97c88a..edd9167ef7 100644
--- a/libavcodec/ac3enc.c
+++ b/libavcodec/ac3enc.c
@@ -1571,11 +1571,10 @@ static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
  */
 static void output_frame_end(AC3EncodeContext *s)
 {
-    int frame_size, frame_size_58, pad_bytes, crc1, crc2, crc_inv;
+    int frame_size_58, pad_bytes, crc1, crc2, crc_inv;
     uint8_t *frame;
 
-    frame_size    = s->frame_size;
-    frame_size_58 = ((frame_size >> 2) + (frame_size >> 4)) << 1;
+    frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
 
     /* pad the remainder of the frame with zeros */
     flush_put_bits(&s->pb);
@@ -1596,8 +1595,8 @@ static void output_frame_end(AC3EncodeContext *s)
     /* compute crc2 */
     crc2 = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
                              frame + frame_size_58,
-                             frame_size - frame_size_58 - 2));
-    AV_WB16(frame + frame_size - 2, crc2);
+                             s->frame_size - frame_size_58 - 2));
+    AV_WB16(frame + s->frame_size - 2, crc2);
 }