diff --git a/CHANGES b/CHANGES
index 561a7d6083..8f0ec315f6 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,7 @@
 Next release
 ============
 
+* FIX: remove unused mandatory flag from spm normalize (https://github.com/nipy/nipype/pull/1048)
 * ENH: Update ANTSCorticalThickness interface (https://github.com/nipy/nipype/pull/1013)
 * FIX: Edge case with sparsemodels and PEP8 cleanup (https://github.com/nipy/nipype/pull/1046)
 * ENH: New io interfaces for JSON files reading/writing (https://github.com/nipy/nipype/pull/1020)
diff --git a/nipype/interfaces/spm/preprocess.py b/nipype/interfaces/spm/preprocess.py
index 19307c73f0..133d061a04 100644
--- a/nipype/interfaces/spm/preprocess.py
+++ b/nipype/interfaces/spm/preprocess.py
@@ -544,7 +544,7 @@ class Normalize12InputSpec(SPMCommandInputSpec):
                             desc='FWHM of Gaussian smoothness of bias')
     tpm = File(exists=True, field='eoptions.tpm',
                desc='template in form of tissue probablitiy maps to normalize to',
-               mandatory=False, xor=['deformation_file'],
+               xor=['deformation_file'],
                copyfile=False)
     affine_regularization_type = traits.Enum('mni', 'size', 'none',
                                              field='eoptions.affreg',
diff --git a/nipype/interfaces/spm/tests/test_auto_Normalize12.py b/nipype/interfaces/spm/tests/test_auto_Normalize12.py
index d11529ddb0..eb93c5d432 100644
--- a/nipype/interfaces/spm/tests/test_auto_Normalize12.py
+++ b/nipype/interfaces/spm/tests/test_auto_Normalize12.py
@@ -37,7 +37,6 @@ def test_Normalize12_inputs():
     ),
     tpm=dict(copyfile=False,
     field='eoptions.tpm',
-    mandatory=False,
     xor=['deformation_file'],
     ),
     use_mcr=dict(),