diff --git a/ebook_converter/__init__.py b/ebook_converter/__init__.py
index 13f8fae..767a4a2 100644
--- a/ebook_converter/__init__.py
+++ b/ebook_converter/__init__.py
@@ -210,18 +210,3 @@ def force_unicode(obj, enc=constants_old.preferred_encoding):
                     if isinstance(obj, bytes):
                         obj = obj.decode('utf-8')
     return obj
-
-
-def human_readable(size, sep=' '):
-    """ Convert a size in bytes into a human readable form """
-    divisor, suffix = 1, "B"
-    for i, candidate in enumerate(('B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB')):
-        if size < (1 << ((i + 1) * 10)):
-            divisor, suffix = (1 << (i * 10)), candidate
-            break
-    size = str(float(size)/divisor)
-    if size.find(".") > -1:
-        size = size[:size.find(".")+2]
-    if size.endswith('.0'):
-        size = size[:-2]
-    return size + sep + suffix
diff --git a/ebook_converter/utils/formatter_functions.py b/ebook_converter/utils/formatter_functions.py
index b12ab93..3f08dbb 100644
--- a/ebook_converter/utils/formatter_functions.py
+++ b/ebook_converter/utils/formatter_functions.py
@@ -6,7 +6,6 @@ Created on 13 Jan 2011
 import inspect, re, traceback, numbers
 from math import trunc
 
-from ebook_converter import human_readable
 from ebook_converter.constants_old import DEBUG
 from ebook_converter.ebooks.metadata import title_sort
 from ebook_converter.utils.config_base import tweaks
@@ -860,15 +859,29 @@ class BuiltinHumanReadable(BuiltinFormatterFunction):
     arg_count = 1
     category = 'Formatting values'
     __doc__ = doc = ('human_readable(v) -- return a string '
-                      'representing the number v in KB, MB, GB, etc.'
-            )
+                     'representing the number v in KB, MB, GB, etc.')
 
     def evaluate(self, formatter, kwargs, mi, locals, val):
         try:
-            return human_readable(round(float(val)))
-        except:
+            return self.human_readable(round(float(val)))
+        except Exception:
             return ''
 
+    def _human_readable(self, size, sep=' '):
+        """ Convert a size in bytes into a human readable form """
+        divisor, suffix = 1, "B"
+        for i, candidate in enumerate(('B', 'KB', 'MB', 'GB', 'TB', 'PB',
+                                       'EB')):
+            if size < (1 << ((i + 1) * 10)):
+                divisor, suffix = (1 << (i * 10)), candidate
+                break
+        size = str(float(size)/divisor)
+        if size.find(".") > -1:
+            size = size[:size.find(".")+2]
+        if size.endswith('.0'):
+            size = size[:-2]
+        return size + sep + suffix
+
 
 class BuiltinFormatNumber(BuiltinFormatterFunction):
     name = 'format_number'