diff --git a/fsl/data/image.py b/fsl/data/image.py
index 4c22ad402e0959d7c2a8b5663621b27b1212025c..8fcaff967594bfa1c9f5662e3b8b1e4185fd7bb1 100644
--- a/fsl/data/image.py
+++ b/fsl/data/image.py
@@ -36,7 +36,6 @@ import                      os
 import os.path           as op
 import                      string
 import                      logging
-import                      collections
 
 import                      six
 import                      deprecation
@@ -58,6 +57,35 @@ import fsl.data.imagewrapper as imagewrapper
 log = logging.getLogger(__name__)
 
 
+ALLOWED_EXTENSIONS = ['.nii.gz', '.nii', '.img', '.hdr', '.img.gz', '.hdr.gz']
+"""The file extensions which we understand. This list is used as the default
+if the ``allowedExts`` parameter is not passed to any of the functions
+below.
+"""
+
+
+EXTENSION_DESCRIPTIONS = ['Compressed NIFTI images',
+                          'NIFTI images',
+                          'ANALYZE75 images',
+                          'NIFTI/ANALYZE75 headers',
+                          'Compressed NIFTI/ANALYZE75 images',
+                          'Compressed NIFTI/ANALYZE75 headers']
+"""Descriptions for each of the extensions in :data:`ALLOWED_EXTENSIONS`. """
+
+
+FILE_GROUPS = [('.hdr',    '.img'),
+               ('.hdr.gz', '.img.gz')]
+"""File suffix groups used by :func:`addExt` to resolve file path
+ambiguities - see :func:`fsl.utils.path.addExt`.
+"""
+
+
+PathError = fslpath.PathError
+"""Error raised by :mod:`fsl.utils.path` functions when an error occurs.
+Made available in this module for convenience.
+"""
+
+
 class Nifti(notifier.Notifier, meta.Meta):
     """The ``Nifti`` class is intended to be used as a base class for
     things which either are, or are associated with, a NIFTI image.
@@ -1290,35 +1318,6 @@ class Image(Nifti):
                 self.notify(topic='dataRange')
 
 
-ALLOWED_EXTENSIONS = ['.nii.gz', '.nii', '.img', '.hdr', '.img.gz', '.hdr.gz']
-"""The file extensions which we understand. This list is used as the default
-if the ``allowedExts`` parameter is not passed to any of the functions
-below.
-"""
-
-
-EXTENSION_DESCRIPTIONS = ['Compressed NIFTI images',
-                          'NIFTI images',
-                          'ANALYZE75 images',
-                          'NIFTI/ANALYZE75 headers',
-                          'Compressed NIFTI/ANALYZE75 images',
-                          'Compressed NIFTI/ANALYZE75 headers']
-"""Descriptions for each of the extensions in :data:`ALLOWED_EXTENSIONS`. """
-
-
-FILE_GROUPS = [('.hdr',    '.img'),
-               ('.hdr.gz', '.img.gz')]
-"""File suffix groups used by :func:`addExt` to resolve file path
-ambiguities - see :func:`fsl.utils.path.addExt`.
-"""
-
-
-PathError = fslpath.PathError
-"""Error raised by :mod:`fsl.utils.path` functions when an error occurs.
-Made available in this module for convenience.
-"""
-
-
 def looksLikeImage(filename, allowedExts=None):
     """Returns ``True`` if the given file looks like a NIFTI image, ``False``
     otherwise.