diff --git a/WebAssembly.asciidoc b/WebAssembly.asciidoc
index c5a54354..85396455 100644
--- a/WebAssembly.asciidoc
+++ b/WebAssembly.asciidoc
@@ -90,6 +90,7 @@ Then serve the three files (`index.html`, `wasm_exec.js`, and
 https://github.com/shurcooL/goexec#goexec[`goexec`]:
 
 ```sh
+# install goexec: go get -u github.com/shurcooL/goexec
 $ goexec 'http.ListenAndServe(":8080", http.FileServer(http.Dir(".")))'
 ```