diff --git a/libavcodec/4xm.c b/libavcodec/4xm.c
index 2ee742fccd..5321b103af 100644
--- a/libavcodec/4xm.c
+++ b/libavcodec/4xm.c
@@ -498,8 +498,8 @@ static int decode_i_block(FourXContext *f, int16_t *block)
 {
     int code, i, j, level, val;
 
-    if (get_bits_left(&f->gb) < 2){
-        av_log(f->avctx, AV_LOG_ERROR, "%d bits left before decode_i_block()\n", get_bits_left(&f->gb));
+    if (get_bits_left(&f->pre_gb) < 2) {
+        av_log(f->avctx, AV_LOG_ERROR, "%d bits left before decode_i_block()\n", get_bits_left(&f->pre_gb));
         return AVERROR_INVALIDDATA;
     }