diff --git a/fsl/wrappers/fugue.py b/fsl/wrappers/fugue.py
index b98841fd728cfdcec0cf265f0e754c2d4bd73495..e7ff7bd8eaabdf409ca3a4a9d10c8ab1df28a192 100644
--- a/fsl/wrappers/fugue.py
+++ b/fsl/wrappers/fugue.py
@@ -86,9 +86,11 @@ def prelude(**kwargs):
 
 @wutils.fileOrImage('phase_image', 'magnitude_image', 'out_image')
 @wutils.fslwrapper
-def fsl_prepare_fieldmap(scanner, phase_image, magnitude_image, out_image, deltaTE, **kwargs):
-    """Wrapper for the ``fsl_prepare_fieldmap`` command."""
-        
+def fsl_prepare_fieldmap(phase_image, magnitude_image, out_image, deltaTE, scanner=None, **kwargs):
+    """Wrapper for the ``fsl_prepare_fieldmap`` command. <scanner> defaults to 'SIEMENS'"""
+    if scanner is None:
+        scanner = 'SIEMENS'
+    
     valmap = {
         'nocheck' : wutils.SHOW_IF_TRUE,
     }
diff --git a/tests/test_wrappers/test_wrappers.py b/tests/test_wrappers/test_wrappers.py
index a85c4b164c3f8cf41ee537d0b833e19d78a849b5..dbffff1d6958202bade7e104cc211e964041c0e4 100644
--- a/tests/test_wrappers/test_wrappers.py
+++ b/tests/test_wrappers/test_wrappers.py
@@ -389,8 +389,7 @@ def test_tbss():
 def test_fsl_prepare_fieldmap():
     with asrt.disabled(), run.dryrun(), mockFSLDIR(bin=('fsl_prepare_fieldmap',)) as fsldir:
         fpf = op.join(fsldir, 'bin', 'fsl_prepare_fieldmap')
-        result   = fw.fsl_prepare_fieldmap(scanner='SIEMENS', 
-                                                 phase_image='ph', 
+        result   = fw.fsl_prepare_fieldmap(phase_image='ph', 
                                                  magnitude_image='mag', 
                                                  out_image='out', 
                                                  deltaTE=2.46,