diff --git a/assignments/a4/a4.tex b/assignments/a4/a4.tex
index fa3290d..10c3ab1 100644
--- a/assignments/a4/a4.tex
+++ b/assignments/a4/a4.tex
@@ -104,6 +104,7 @@ By definition of $g \in \cO(f)$, we know $g(n) \leq c_0 \cdot f(n)$.
     g(n) &\leq c_0 \cdot (\floor{f(n)} + \floor{f(n)}) \quad{\text{because } 1 \leq \floor{f(n)}} \\
     g(n) &\leq 2c_0 \cdot \floor{f(n)}\\
     g(n) &\leq c_1 \cdot \floor{f(n)}
+\end{align*}
 \end{proof}
 
 \end{enumerate}