diff --git a/report.tex b/report.tex
index 4104b1e..fc29293 100644
--- a/report.tex
+++ b/report.tex
@@ -310,7 +310,7 @@
     \end{equation}
     The evolution of the constraints is given by
     \begin{equation}
-      \Partial{t} \mathcal{C}_i = 0,
+      \Partial{t} \mathcal{C}_i = \Partial{i} \pi - \Partial{i} \Partial{t} \phi = 0,
     \end{equation}
     which means that if the constraints are satisfied initially, they will be satisfied for all time. However, in numerical simulations, there will always be some constraint violation due to numerical errors, and thus it's better to add some constraint damping terms to the evolution equations to suppress the growth of constraint violation.
   \end{frame}