diff --git a/tests/test_fslsub.py b/tests/test_fslsub.py
index 93e96a2366cb5e98623129eed602cd7838166d7c..40d7668285c813b332c8da91574cc34ffa671681 100644
--- a/tests/test_fslsub.py
+++ b/tests/test_fslsub.py
@@ -147,28 +147,31 @@ def test_add_to_parser():
         ('-F', ),
         ('-s', 'pename,thread')
     ]
-    for flag in test_flags:
-        for include in (None, [flag[0]]):
-            parser = argparse.ArgumentParser("test parser")
-            fslsub.SubmitParams.add_to_parser(parser, include=include)
-            args = parser.parse_args(flag)
-            submitter = fslsub.SubmitParams.from_args(args)
-            assert submitter.as_flags() == flag
-
-    parser = argparse.ArgumentParser("test parser")
-    parser.add_argument('some_input')
-    fslsub.SubmitParams.add_to_parser(parser, include=None)
-    all_flags = tuple(part for flag in test_flags for part in flag)
-    args = parser.parse_args(('input', ) + all_flags)
-    assert args.some_input == 'input'
-    submitter = fslsub.SubmitParams.from_args(args)
-    assert len(all_flags) == len(submitter.as_flags())
-    for flag in test_flags:
-        res_flags = submitter.as_flags()
-        assert flag[0] in res_flags
-        start_index = res_flags.index(flag[0])
-        for idx, part in enumerate(flag):
-            assert res_flags[idx + start_index] == part
+    with fslsub_mockFSLDIR():
+        for flag in test_flags:
+            for include in (None, [flag[0]]):
+                parser = argparse.ArgumentParser("test parser")
+                fslsub.SubmitParams.add_to_parser(parser, include=include)
+                args = parser.parse_args(flag)
+                submitter = fslsub.SubmitParams.from_args(args)
+                assert submitter.as_flags() == flag
+
+    with fslsub_mockFSLDIR():
+        parser = argparse.ArgumentParser("test parser")
+        parser.add_argument('some_input')
+        fslsub.SubmitParams.add_to_parser(parser, include=None)
+        all_flags = tuple(part for flag in test_flags for part in flag)
+        args = parser.parse_args(('input', ) + all_flags)
+        assert args.some_input == 'input'
+        submitter = fslsub.SubmitParams.from_args(args)
+        assert len(all_flags) == len(submitter.as_flags())
+
+        for flag in test_flags:
+            res_flags = submitter.as_flags()
+            assert flag[0] in res_flags
+            start_index = res_flags.index(flag[0])
+            for idx, part in enumerate(flag):
+                assert res_flags[idx + start_index] == part
 
 
 def myfunc():