diff --git a/README.md b/README.md
index 47b09df1fd0232905cc8130e9dca4bc80f902276..86cc86a9d62fc748847b082686a92121df1ea535 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ GESAs are constructed from ESAs using a generalization of the merging
method from [2].
**NOTE** currently Algorithm 5.21 [2] is implemented with a
-worst-case O(n^2^) complexity. We should implement Section 5.5.5 [2],
+worst-case O( n^2 ) complexity. We should implement Section 5.5.5 [2],
which is based on [3].
## References