diff --git a/nibabel/freesurfer/mghformat.py b/nibabel/freesurfer/mghformat.py
index b3dd1f9bc5..927d6126c0 100644
--- a/nibabel/freesurfer/mghformat.py
+++ b/nibabel/freesurfer/mghformat.py
@@ -255,7 +255,7 @@ def get_zooms(self):
         .. _mghformat: https://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/MghFormat#line-82
         '''
         # Do not return time zoom (TR) if 3D image
-        tzoom = (self['tr'],)[:self._ndims() > 3]
+        tzoom = (self['tr'],) if self._ndims() > 3 else ()
         return tuple(self._structarr['delta']) + tzoom
 
     def set_zooms(self, zooms):