diff --git a/nipype/interfaces/c3.py b/nipype/interfaces/c3.py
index fa7152f3e0..45c1319715 100644
--- a/nipype/interfaces/c3.py
+++ b/nipype/interfaces/c3.py
@@ -2,22 +2,26 @@
                                     File)
 from nipype.interfaces.slicer.base import SlicerCommandLine
 
+
 class C3dAffineToolInputSpec(CommandLineInputSpec):
     reference_file = File(exists=True, argstr="-ref %s", position=1)
-    source_file =  File(exists=True, argstr='-src %s', position=2)
+    source_file = File(exists=True, argstr='-src %s', position=2)
     transform_file = File(exists=True, argstr='%s', position=3)
-    itk_transform = traits.Either(traits.Bool, File(), hash_files=False, desc="Export ITK transform.", argstr="-oitk %s", position=5)
+    itk_transform = traits.Either(traits.Bool, File(), hash_files=False,
+                                  desc="Export ITK transform.",
+                                  argstr="-oitk %s", position=5)
     fsl2ras = traits.Bool(argstr='-fsl2ras', position=4)
 
 
 class C3dAffineToolOutputSpec(TraitedSpec):
     itk_transform = File(exists=True)
 
+
 class C3dAffineTool(SlicerCommandLine):
     """Converts fsl-style Affine registration into ANTS compatible itk format
     """
-    input_spec=C3dAffineToolInputSpec
-    output_spec=C3dAffineToolOutputSpec
+    input_spec = C3dAffineToolInputSpec
+    output_spec = C3dAffineToolOutputSpec
 
     _cmd = 'c3d_affine_tool'
-    _outputs_filenames = {'itk_transform':'affine.txt'}
+    _outputs_filenames = {'itk_transform': 'affine.txt'}