diff --git a/tests/test_pysnooper.py b/tests/test_pysnooper.py
index 81f7102..b32fe92 100644
--- a/tests/test_pysnooper.py
+++ b/tests/test_pysnooper.py
@@ -150,7 +150,7 @@ def test_method_and_prefix():
         def __init__(self):
             self.x = 2
 
-        @pysnooper.snoop(variables=('self.x'), prefix='ZZZ')
+        @pysnooper.snoop(variables=('self.x',), prefix='ZZZ')
         def square(self):
             foo = 7
             self.x **= 2
@@ -167,11 +167,13 @@ def test_method_and_prefix():
     assert_output(
         output,
         (
-            VariableEntry(prefix='ZZZ'),
+            VariableEntry('self', prefix='ZZZ'),
+            VariableEntry('self.x', '2', prefix='ZZZ'),
             CallEntry('def square(self):', prefix='ZZZ'),
             LineEntry('foo = 7', prefix='ZZZ'),
             VariableEntry('foo', '7', prefix='ZZZ'),
             LineEntry('self.x **= 2', prefix='ZZZ'),
+            VariableEntry('self.x', '4', prefix='ZZZ'),
             LineEntry(prefix='ZZZ'),
             ReturnEntry(prefix='ZZZ'),
             ReturnValueEntry(prefix='ZZZ'),