diff --git a/nipype/interfaces/fsl/maths.py b/nipype/interfaces/fsl/maths.py
index 9e05b4d102..f3276024b7 100644
--- a/nipype/interfaces/fsl/maths.py
+++ b/nipype/interfaces/fsl/maths.py
@@ -41,7 +41,7 @@ class MathsInput(FSLCommandInputSpec):
 
 class MathsOutput(TraitedSpec):
 
-    out_file = File(exists=True, desc="image written after calculations")
+    out_file = File(desc="image written after calculations")
 
 
 class MathsCommand(FSLCommand):