diff --git a/libavcodec/iff.c b/libavcodec/iff.c
index 8e7f8cae46..b4b99a5101 100644
--- a/libavcodec/iff.c
+++ b/libavcodec/iff.c
@@ -832,9 +832,9 @@ static int decode_frame(AVCodecContext *avctx,
         break;
     case 4:
         bytestream2_init(&gb, buf, buf_size);
-        if (avctx->codec_tag == MKTAG('R','G','B','8'))
+        if (avctx->codec_tag == MKTAG('R','G','B','8') && avctx->pix_fmt == AV_PIX_FMT_RGB32)
             decode_rgb8(&gb, s->frame.data[0], avctx->width, avctx->height, s->frame.linesize[0]);
-        else if (avctx->codec_tag == MKTAG('R','G','B','N'))
+        else if (avctx->codec_tag == MKTAG('R','G','B','N') && avctx->pix_fmt == AV_PIX_FMT_RGB444)
             decode_rgbn(&gb, s->frame.data[0], avctx->width, avctx->height, s->frame.linesize[0]);
         else
             return unsupported(avctx);