diff --git a/lasp/lasp_common.py b/lasp/lasp_common.py
index f6003c9..10a1b31 100644
--- a/lasp/lasp_common.py
+++ b/lasp/lasp_common.py
@@ -336,11 +336,11 @@ class FreqWeighting:
     """
     Frequency weighting types
     """
+    Z = ('Z', 'Z-weighting')
     A = ('A', 'A-weighting')
     C = ('C', 'C-weighting')
-    Z = ('Z', 'Z-weighting')
     types = (A, C, Z)
-    default = A
+    default = Z
     default_index = 0
 
     @staticmethod
diff --git a/lasp/lasp_measurement.py b/lasp/lasp_measurement.py
index 5f96d0d..3373a26 100644
--- a/lasp/lasp_measurement.py
+++ b/lasp/lasp_measurement.py
@@ -208,11 +208,16 @@ class Measurement:
             self.N = (self.nblocks * self.blocksize)
             self.T = self.N / self.samplerate
 
+            # Due to a previous bug, the channel names were not stored
+            # consistently, i.e. as 'channel_names' and later camelcase.
             try:
-                self._channel_names = f.attrs['channel_names']
+                self._channelNames = f.attrs['channel_names']
             except KeyError:
-                # No channel names found in measurement file
-                self._channel_names = [f'Unnamed {i}' for i in range(self.nchannels)]
+                try:
+                    self._channelNames = f.attrs['channelNames']
+                except KeyError:
+                    # No channel names found in measurement file
+                    self._channelNames = [f'Unnamed {i}' for i in range(self.nchannels)]
 
             # comment = read-write thing
             try:
@@ -232,7 +237,6 @@ class Measurement:
 
             self._time = f.attrs['time']
 
-
             try:
                 qtys_json = f.attrs['qtys']
                 # Load quantity data
@@ -244,10 +248,14 @@ class Measurement:
                 self._qtys = [SIQtys.default for i in range(self.nchannels)]
 
     def setAttribute(self, atrname, value):
+        """
+        Set an attribute in the measurement file, and keep a local copy in
+        memory for efficient accessing.
+        """
         with self.file('r+') as f:
             # Update comment attribute in the file
             f.attrs[atrname] = value
-            setattr(self, '_' + atrname, value)
+        setattr(self, '_' + atrname, value)
 
     @property
     def name(self):
@@ -256,7 +264,7 @@ class Measurement:
 
     @property
     def channelNames(self):
-        return self._channel_names
+        return self._channelNames
 
     @channelNames.setter
     def channelNames(self, newchnames):
diff --git a/setup.py b/setup.py
index 322e3f6..409e566 100644
--- a/setup.py
+++ b/setup.py
@@ -27,16 +27,16 @@ setup(
       long_description_content_type="text/markdown",
       # ext_modules=[CMakeExtension('lasp/wrappers.so'),
       #              ],
-      package_data={'lasp': ['wrappers.so']},
+      #package_data={'lasp': ['wrappers.so']},
       author='J.A. de Jong - ASCEE',
       author_email="j.a.dejong@ascee.nl",
       install_requires=['matplotlib>=1.0',
-                        'scipy>=1.0', 'numpy>=1.0', 'h5py',
-                        'dataclasses_json',
+                        'scipy>=1.0', 'numpy>=1.0', 'h5py==3.2.0',
+                        'dataclasses_json', 'cython',
                         ],
       license='MIT',
       description="Library for Acoustic Signal Processing",
       keywords="",
-      url="https://www.ascee.nl/lasp/",   # project home page, if any
+      url="https://www.ascee.nl/lasp/",   # project home page
 
 )