diff --git a/libavcodec/faxcompr.c b/libavcodec/faxcompr.c
index 155f78da66..44d27219ff 100644
--- a/libavcodec/faxcompr.c
+++ b/libavcodec/faxcompr.c
@@ -296,7 +296,8 @@ int ff_ccitt_unpack(AVCodecContext *avctx, const uint8_t *src, int srcsize,
     ref[0] = avctx->width;
     ref[1] = 0;
     ref[2] = 0;
-    init_get_bits(&gb, src, srcsize * 8);
+    if ((ret = init_get_bits8(&gb, src, srcsize)) < 0)
+        return ret;
     has_eol = show_bits(&gb, 12) == 1 || show_bits(&gb, 16) == 1;
 
     for (j = 0; j < height; j++) {