diff --git a/fsl/utils/platform.py b/fsl/utils/platform.py
index 9b95faf966326ce116c058bbb54517ce2185541f..05bbd1a649b8e396408e5781f01c95a1fecb64b6 100644
--- a/fsl/utils/platform.py
+++ b/fsl/utils/platform.py
@@ -179,7 +179,8 @@ class Platform(notifier.Notifier):
         """Changes the value of the :attr:`fsldir` property, and notifies any
         registered listeners.
         """
-        self.__fsldir = value
+        self.__fsldir        = value
+        os.environ['FSLDIR'] = value
         self.notify()