diff --git a/README.md b/README.md
index 079cdce..92c3397 100644
--- a/README.md
+++ b/README.md
@@ -149,7 +149,7 @@ expr.evaluate({'x': 2})  # 6.283185307179586
 # get variables
 expr = parser.parse('x * (y * atan(1))')
 expr.variables()  # ['x', 'y']
-expr.simplify({'y': 4}).variables()  # ['x']
+expr.simplify({'y': 4}).variables()  # ['x']
 ```
 
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