diff --git a/examples/libreoffice/Dockerfile b/examples/libreoffice/Dockerfile
index fee75bb..9cc8a59 100644
--- a/examples/libreoffice/Dockerfile
+++ b/examples/libreoffice/Dockerfile
@@ -8,5 +8,5 @@ COPY cmd.sh /app/
 RUN apk update && \
   apk add --no-cache \
     openjdk17-jre==17.0.11_p9-r0 \
-    libreoffice==7.6.3.1-r0 \
+    libreoffice==7.6.7.2-r0 \
     ttf-dejavu==2.37-r5
diff --git a/main.go b/main.go
index e49e732..e09a552 100644
--- a/main.go
+++ b/main.go
@@ -76,6 +76,10 @@ func MessageHandler(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusMethodNotAllowed)
 		return
 	}
+	if r.Header.Get("Apix-Ldp-Resource") == "" {
+		http.Error(w, "Bad request", http.StatusBadRequest)
+		return
+	}
 	defer r.Body.Close()
 
 	// Read the Alpaca message payload