diff --git a/lecture04/lecture04.tex b/lecture04/lecture04.tex
index c41527d..31d5739 100644
--- a/lecture04/lecture04.tex
+++ b/lecture04/lecture04.tex
@@ -180,7 +180,7 @@ \subsubsection*{Amplitude Properties}
 
     \item  \emph{Homogeneity}: A system is homogeneous if it satisfies the equation
     \[
-		\mathcal{S}[\alpha f_i[n, m]] = \alpha\mathcal{S}[f_i[n, m]
+		\mathcal{S}[\alpha f_i[n, m]] = \alpha\mathcal{S}[f_i[n, m]]
     \]
 	
     \item \emph{Superposition}: A system has the property of superposition if it satisfies the equation