diff --git a/filetimelapse.py b/filetimelapse.py
index 0db8953..b51603f 100644
--- a/filetimelapse.py
+++ b/filetimelapse.py
@@ -24,7 +24,7 @@ def hash_file(filepath, hasher):
 def hash_file_md5(filepath):
     return hash_file(filepath, hasher=hashlib.md5())
 
-def read_filebytes(filepath, chunk_size=bytestring.MIBIBYTE):
+def read_filebytes(filepath, chunk_size=bytestring.MEBIBYTE):
     filepath = pathclass.Path(filepath)
     if not filepath.is_file:
         raise FileNotFoundError(filepath)
diff --git a/rarpar.py b/rarpar.py
index 526fa31..a64a5ba 100644
--- a/rarpar.py
+++ b/rarpar.py
@@ -269,7 +269,7 @@ def _normalize_volume(volume, pathsize):
         if volume.endswith('%'):
             volume = volume[:-1]
             volume = float(volume) / 100
-            volume = (pathsize * volume) / bytestring.MIBIBYTE
+            volume = (pathsize * volume) / bytestring.MEBIBYTE
             volume = max(1, volume)
             return int(volume)