diff --git a/WebAssembly.md b/WebAssembly.md
index 78131c4b..bfa1e3bc 100644
--- a/WebAssembly.md
+++ b/WebAssembly.md
@@ -41,6 +41,7 @@ import (
 	"flag"
 	"log"
 	"net/http"
+	"strings"
 )
 
 var (
@@ -51,7 +52,13 @@ var (
 func main() {
 	flag.Parse()
 	log.Printf("listening on %q...", *listen)
-	log.Fatal(http.ListenAndServe(*listen, http.FileServer(http.Dir(*dir))))
+	log.Fatal(http.ListenAndServe(*listen, http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
+		if strings.HasSuffix(req.URL.Path, ".wasm") {
+			resp.Header().Set("content-type", "application/wasm")
+		}
+
+		http.FileServer(http.Dir(*dir)).ServeHTTP(resp, req)
+	})))
 }
 ```