diff --git a/libavcodec/ppc/idctdsp.c b/libavcodec/ppc/idctdsp.c
index 6cc660faa8..419f18802f 100644
--- a/libavcodec/ppc/idctdsp.c
+++ b/libavcodec/ppc/idctdsp.c
@@ -249,7 +249,7 @@ av_cold void ff_idctdsp_init_ppc(IDCTDSPContext *c, AVCodecContext *avctx,
 #if HAVE_ALTIVEC
     if (PPC_ALTIVEC(av_get_cpu_flags())) {
         if (!high_bit_depth && avctx->lowres == 0) {
-            if ((avctx->idct_algo == FF_IDCT_AUTO) ||
+            if ((avctx->idct_algo == FF_IDCT_AUTO && !(avctx->flags & CODEC_FLAG_BITEXACT)) ||
                 (avctx->idct_algo == FF_IDCT_ALTIVEC)) {
                 c->idct      = idct_altivec;
                 c->idct_add  = idct_add_altivec;