diff --git a/binascii/binascii.py b/binascii/binascii.py
index 2b7cf6fe..dd6744c2 100644
--- a/binascii/binascii.py
+++ b/binascii/binascii.py
@@ -68,7 +68,7 @@ def a2b_base64(ascii):
             #
             if leftbits >= 8:
                 leftbits -= 8
-                res.append((leftchar >> leftbits).to_bytes(1))
+                res.append((leftchar >> leftbits).to_bytes(1, 'big'))
                 leftchar &= ((1 << leftbits) - 1)
             #
             last_char_was_a_pad = False
diff --git a/binascii/metadata.txt b/binascii/metadata.txt
index e389e185..917f31ce 100644
--- a/binascii/metadata.txt
+++ b/binascii/metadata.txt
@@ -1,3 +1,3 @@
 srctype=pypy
 type=module
-version = 2.4.0-4
+version = 2.4.0-5
diff --git a/binascii/setup.py b/binascii/setup.py
index 164fcde3..63756cc5 100644
--- a/binascii/setup.py
+++ b/binascii/setup.py
@@ -7,7 +7,7 @@ sys.path.append("..")
 import optimize_upip
 
 setup(name='micropython-binascii',
-      version='2.4.0-4',
+      version='2.4.0-5',
       description='PyPy binascii module ported to MicroPython',
       long_description='This is a module ported from PyPy standard library to be compatible with\nMicroPython interpreter. Usually, this means applying small patches for\nfeatures not supported (yet, or at all) in MicroPython. Sometimes, heavier\nchanges are required. Note that CPython modules are written with availability\nof vast resources in mind, and may not work for MicroPython ports with\nlimited heap. If you are affected by such a case, please help reimplement\nthe module from scratch.',
       url='https://github.com/micropython/micropython-lib',