diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -51,7 +51,7 @@ This is an up to date list of available keyword options:
   - `store_overlap`:  bool, default True. Store the overlaps for later usage in calling guess without passing the current overlap. It can be disabled for performance, but calling guess will require passing the overlap.
 
 Some options can be piped to the fitting modules.
-  - `fitting_regularization`: float, default 0.0. Controls the regularization for both the "leastsquare" and "qtr" fitting schemes. In both the fitting schemes, an additional term of the form $\epsilon^2 ||\alpha||^2$ is added to the error function, in this expression $\alpha$ is the vector of coefficients.
+  - `fitting_regularization`: float, default 0.0. Controls the regularization for both the "leastsquare" and "qtr" fitting schemes. In both the fitting schemes, an additional term of the form $\varepsilon^2 ||\alpha||^2$ is added to the error function, in this expression $\alpha$ is the vector of coefficients and $\varepsilon$ is the regularization.
 
 
 ## Acknowledgments