diff --git a/report.tex b/report.tex
index cf45df9..19793c3 100644
--- a/report.tex
+++ b/report.tex
@@ -261,7 +261,7 @@
     \begin{equation}
       \begin{cases}
         \Partial{t}{\phi} = \pi, \\
-        \Partial{t}{\tensor{\psi}{_i}} = \pdv{\pi}{x}, \\
+        \Partial{t}{\tensor{\psi}{_i}} = \Partial{i} \pi, \\
         \Partial{t}{\pi} = \pdv{\tensor{\psi}{_i}}{x}.
       \end{cases}
     \end{equation}