diff --git a/v1/runtime/runtime.go b/v1/runtime/runtime.go
index 26d830fa790..38503c5f39d 100644
--- a/v1/runtime/runtime.go
+++ b/v1/runtime/runtime.go
@@ -854,7 +854,10 @@ func (rt *Runtime) Addrs() []string {
 // listening on (when in server mode). Returns an empty list if it hasn't
 // started listening.
 func (rt *Runtime) DiagnosticAddrs() []string {
-	if rt.server == nil {
+	rt.serverInitMtx.RLock()
+	defer rt.serverInitMtx.RUnlock()
+
+	if rt.serverStatus < ServerInitialized {
 		return nil
 	}
 
diff --git a/v1/test/e2e/testing.go b/v1/test/e2e/testing.go
index 844986b7cab..2bcf1712f96 100644
--- a/v1/test/e2e/testing.go
+++ b/v1/test/e2e/testing.go
@@ -309,7 +309,7 @@ func (t *TestRuntime) WaitForServer() error {
 	retries := 100 // 10 seconds before we give up
 	for range retries {
 		// First make sure it has started listening and we have an address
-		if t.URL() != "" {
+		if t.URL() != "" && t.diagnosticAddrsReady() {
 			// Then make sure it has started serving
 			err := t.HealthCheck(t.URL())
 			if err == nil {
@@ -322,6 +322,16 @@ func (t *TestRuntime) WaitForServer() error {
 	return errors.New("API Server not ready in time")
 }
 
+// diagnosticAddrsReady reports whether every configured diagnostic address has
+// been bound. Listeners bind on their own goroutines, so the diagnostic one can
+// still be unbound once the main one is serving.
+func (t *TestRuntime) diagnosticAddrsReady() bool {
+	if t.Params.DiagnosticAddrs == nil {
+		return true
+	}
+	return len(t.Runtime.DiagnosticAddrs()) >= len(*t.Params.DiagnosticAddrs)
+}
+
 func (t *TestRuntime) WaitForServerStatus(status runtime.ServerStatus) error {
 	delay := time.Duration(100) * time.Millisecond
 	retries := 100 // 10 seconds before we give up