diff --git a/src/image-processing-and-computer-vision/module1/sections/_spatial_filtering.tex b/src/image-processing-and-computer-vision/module1/sections/_spatial_filtering.tex
index 0a17b95..b0997e4 100644
--- a/src/image-processing-and-computer-vision/module1/sections/_spatial_filtering.tex
+++ b/src/image-processing-and-computer-vision/module1/sections/_spatial_filtering.tex
@@ -167,7 +167,7 @@ where $\tilde{I}(p)$ is the real information.
                 & \text{sifting property} \\
                 %
                 &= \int_{-\infty}^{+\infty}\int_{-\infty}^{+\infty} T\left\{ i(\alpha, \beta) \delta(x-\alpha, y-\beta) \right\} \,\text{d}\alpha\,\text{d}\beta
-                & \\
+                & \text{linearity of $T\{ \cdot \}$} \\
                 %
                 &= \int_{-\infty}^{+\infty}\int_{-\infty}^{+\infty} i(\alpha, \beta) T\left\{ \delta(x-\alpha, y-\beta) \right\} \,\text{d}\alpha\,\text{d}\beta
                 & \text{linearity of $T\{ \cdot \}$} \\