diff --git a/docs.it4i/software/viz/insitu.md b/docs.it4i/software/viz/insitu.md
index c8441999f5565ff4b2b817127d4919849b2b4f16..2fb5eb4ba7b86c83cc1b4d1f481d55d2567bf0a0 100644
--- a/docs.it4i/software/viz/insitu.md
+++ b/docs.it4i/software/viz/insitu.md
@@ -48,7 +48,7 @@ It will generate the CxxFullExampleAdaptor executable file. This can be later ru
 Provided example is a simple MPI program. Main executing part is written in FEDriver.cxx. It is a simulator code that creates computational grid   
 
 
-```javascript
+```javascript {.line-numbers}
 #include ahoj.h
 
 int main() {