diff --git a/Physics/Advanced/Fluid_mechanics/Fluid_mechanics.tex b/Physics/Advanced/Fluid_mechanics/Fluid_mechanics.tex
index 73d6e78..2fc451d 100644
--- a/Physics/Advanced/Fluid_mechanics/Fluid_mechanics.tex
+++ b/Physics/Advanced/Fluid_mechanics/Fluid_mechanics.tex
@@ -161,7 +161,7 @@
   \begin{proof}
     Note that:
     $$
-      \dv{}{t}\int_{W_t}\dd{V}=\dv{}{t}\int_WJ\dd{V}=\int_{W_t}\div\vf{u}\dd{V}
+      \dv{}{t}\int_{W_t}\dd{V}=\dv{}{t}\int_WJ\dd{V}=\int_{W_t}J\div\vf{u}\dd{V}
     $$
     Hence, if $\div \vf{u}=0$ then the flow is incompressible. Now, if the flow is incompressible we have that:
     $$