diff --git a/lib/diagnostics_channel.js b/lib/diagnostics_channel.js
index 998f17aa61d..7c1f4fa845e 100644
--- a/lib/diagnostics_channel.js
+++ b/lib/diagnostics_channel.js
@@ -229,6 +229,7 @@ class Channel {
   }
 
   subscribe(subscription) {
+    validateFunction(subscription, 'subscription');
     markActive(this);
     this.subscribe(subscription);
   }
diff --git a/test/parallel/test-diagnostics-channel-object-channel-pub-sub.js b/test/parallel/test-diagnostics-channel-object-channel-pub-sub.js
index 9498419b806..f0254493655 100644
--- a/test/parallel/test-diagnostics-channel-object-channel-pub-sub.js
+++ b/test/parallel/test-diagnostics-channel-object-channel-pub-sub.js
@@ -44,3 +44,5 @@ assert.ok(!channel.unsubscribe(subscriber));
 assert.throws(() => {
   channel.subscribe(null);
 }, { code: 'ERR_INVALID_ARG_TYPE' });
+assert.ok(!channel.hasSubscribers);
+assert.ok(!dc.hasSubscribers('test'));
diff --git a/test/parallel/test-diagnostics-channel-pub-sub.js b/test/parallel/test-diagnostics-channel-pub-sub.js
index a7232ab58ce..e3a868b7ce0 100644
--- a/test/parallel/test-diagnostics-channel-pub-sub.js
+++ b/test/parallel/test-diagnostics-channel-pub-sub.js
@@ -42,6 +42,8 @@ assert.ok(!dc.unsubscribe(name, subscriber));
 assert.throws(() => {
   dc.subscribe(name, null);
 }, { code: 'ERR_INVALID_ARG_TYPE' });
+assert.ok(!channel.hasSubscribers);
+assert.ok(!dc.hasSubscribers(name));
 
 // Reaching zero subscribers should not delete from the channels map as there
 // will be no more weakref to incRef if another subscribe happens while the