diff --git a/libhts/libhts.py b/libhts/libhts.py
index b4bfc4796bab4d93b97116c9f1d41e1f9878b6a4..959b1a886b1d590b31061221ce99a9714b6ad7fb 100644
--- a/libhts/libhts.py
+++ b/libhts/libhts.py
@@ -210,7 +210,8 @@ def make_empty_bigwig(filename, chrom_sizes):
     """
     bw_out = pyBigWig.open(filename, "w")
     bw_out.addHeader(list(chrom_sizes.items()))
-    for (chrom, chrom_len) in bw_out.chroms().items():
+    # for (chrom, chrom_len) in bw_out.chroms().items():
+    for (chrom, chrom_len) in chrom_sizes.items():
         bw_out.addEntries(
             chrom, 0,
             values=np.nan_to_num(np.zeros(chrom_len)[0::10]),