diff --git a/src/year2/machine-learning-for-computer-vision/sections/_object_detection.tex b/src/year2/machine-learning-for-computer-vision/sections/_object_detection.tex
index 0375cd8..078a81f 100644
--- a/src/year2/machine-learning-for-computer-vision/sections/_object_detection.tex
+++ b/src/year2/machine-learning-for-computer-vision/sections/_object_detection.tex
@@ -33,7 +33,7 @@
     \item[Intersection over union (\texttt{IoU})] 
     \marginnote{Intersection over union (\texttt{IoU})}
         Measures the amount of overlap between two boxes computed as the ratio of the area of intersection over the area of union:
-        \[ \texttt{IoU}(BB_i, BB_j) = \frac{\vert BB_i \cap BB_j \vert}{\vert BB_i \vert + \vert BB_j \vert - \vert BB_i \cup BB_j \vert} \]
+        \[ \texttt{IoU}(BB_i, BB_j) = \frac{\vert BB_i \cap BB_j \vert}{\vert BB_i \vert + \vert BB_j \vert - \vert BB_i \cap BB_j \vert} \]
 
         \begin{description}
             \item[True/false positive criteria]