diff --git a/Orange/data/variable.py b/Orange/data/variable.py
index 17336695186..20fdc18802f 100644
--- a/Orange/data/variable.py
+++ b/Orange/data/variable.py
@@ -260,10 +260,10 @@ class Variable(Reprable, metaclass=VariableMeta):
         Non-primitive variables must redefine it to return `None`.
 
     .. attribute:: sparse
-    
+
         A flag about sparsity of the variable. When set, the variable suggests
         it is should be stored in a sparse matrix. 
-    
+
     .. attribute:: source_variable
 
         An optional descriptor of the source variable - if any - from which