diff --git a/pyalfe/interfaces/freesurfer.py b/pyalfe/interfaces/freesurfer.py
index 6a28244..cc621a5 100644
--- a/pyalfe/interfaces/freesurfer.py
+++ b/pyalfe/interfaces/freesurfer.py
@@ -7,6 +7,7 @@ def __init__(self):
 
     def mri_synthseg(self, input, output):
         self.cmd += ['mri_synthseg', '--i', input, '--o', output]
+        return self
 
     def run(self):
         return subprocess.run(self.cmd, capture_output=True).stdout.decode("utf-8")