diff --git a/src/held-messages.ts b/src/held-messages.ts
index 5d6813d..e80782f 100644
--- a/src/held-messages.ts
+++ b/src/held-messages.ts
@@ -97,7 +97,7 @@ export class HeldMessages {
 		return this.held.full || this.held.weight >= this.maxOctets;
 	}
 
-	hold(pduObjs: PduObject[], listeners: number): MessageHold {
+	private hold(pduObjs: PduObject[], listeners: number): MessageHold {
 		const hold = new MessageHold({
 			isHeld: () => this.has(pduObjs),
 			release: () => { this.release(pduObjs); },