diff --git a/pybloom/pybloom.py b/pybloom/pybloom.py
index beeefe4..240fe51 100644
--- a/pybloom/pybloom.py
+++ b/pybloom/pybloom.py
@@ -268,9 +268,9 @@ def fromfile(cls, f, n=-1):
         else:
             (filter.bitarray.frombytes(f.read()) if is_string_io(f)
              else filter.bitarray.fromfile(f))
-        if filter.num_bits != filter.bitarray.length() and \
-               (filter.num_bits + (8 - filter.num_bits % 8)
-                != filter.bitarray.length()):
+        if filter.num_bits != len(filter.bitarray) and \
+            (filter.num_bits + (8 - filter.num_bits % 8)
+                != len(filter.bitarray)):
             raise ValueError('Bit length mismatch!')
 
         return filter
diff --git a/setup.py b/setup.py
index 2d07d1e..db86c3f 100644
--- a/setup.py
+++ b/setup.py
@@ -36,6 +36,6 @@
     platforms=['any'],
     test_suite="pybloom.tests",
     zip_safe=True,
-    install_requires=['bitarray>=0.3.4'],
+    install_requires=['bitarray>1.5.1'],
     packages=['pybloom']
 )