diff --git a/cmd/derper/depaware.txt b/cmd/derper/depaware.txt
index 01c278fbd..0a75ac43e 100644
--- a/cmd/derper/depaware.txt
+++ b/cmd/derper/depaware.txt
@@ -139,7 +139,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         tailscale.com/types/structs                                  from tailscale.com/ipn+
         tailscale.com/types/tkatype                                  from tailscale.com/client/local+
         tailscale.com/types/views                                    from tailscale.com/ipn+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/net/netmon
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
         tailscale.com/util/ctxkey                                    from tailscale.com/tsweb+
diff --git a/cmd/k8s-operator/depaware.txt b/cmd/k8s-operator/depaware.txt
index ebd22770e..b800b78c6 100644
--- a/cmd/k8s-operator/depaware.txt
+++ b/cmd/k8s-operator/depaware.txt
@@ -848,7 +848,7 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/cmd/k8s-operator+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/cmd/k8s-operator+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
   LW    tailscale.com/util/cmpver                                    from tailscale.com/net/dns+
diff --git a/cmd/tailscale/depaware.txt b/cmd/tailscale/depaware.txt
index b249639bc..53dc998bd 100644
--- a/cmd/tailscale/depaware.txt
+++ b/cmd/tailscale/depaware.txt
@@ -171,7 +171,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/types/structs                                  from tailscale.com/ipn+
         tailscale.com/types/tkatype                                  from tailscale.com/types/key+
         tailscale.com/types/views                                    from tailscale.com/tailcfg+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/net/netcheck+
         tailscale.com/util/cloudenv                                  from tailscale.com/net/dnscache+
         tailscale.com/util/cmpver                                    from tailscale.com/net/tshttpproxy+
diff --git a/cmd/tailscaled/depaware-min.txt b/cmd/tailscaled/depaware-min.txt
index 224026f25..e750f86e6 100644
--- a/cmd/tailscaled/depaware-min.txt
+++ b/cmd/tailscaled/depaware-min.txt
@@ -144,7 +144,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/control/controlclient+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/appc+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
         tailscale.com/util/ctxkey                                    from tailscale.com/client/tailscale/apitype+
diff --git a/cmd/tailscaled/depaware-minbox.txt b/cmd/tailscaled/depaware-minbox.txt
index 9633e7398..17f1a22b2 100644
--- a/cmd/tailscaled/depaware-minbox.txt
+++ b/cmd/tailscaled/depaware-minbox.txt
@@ -171,7 +171,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/control/controlclient+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/appc+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
         tailscale.com/util/cmpver                                    from tailscale.com/clientupdate
diff --git a/cmd/tailscaled/depaware.txt b/cmd/tailscaled/depaware.txt
index bdc110e1a..1b5bdab91 100644
--- a/cmd/tailscaled/depaware.txt
+++ b/cmd/tailscaled/depaware.txt
@@ -416,7 +416,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/views                                    from tailscale.com/ipn/ipnlocal+
         tailscale.com/util/backoff                                   from tailscale.com/cmd/tailscaled+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/control/controlclient+
         tailscale.com/util/cloudenv                                  from tailscale.com/net/dns/resolver+
         tailscale.com/util/cmpver                                    from tailscale.com/net/dns+
diff --git a/cmd/tsidp/depaware.txt b/cmd/tsidp/depaware.txt
index ebf03b541..21ca122c4 100644
--- a/cmd/tsidp/depaware.txt
+++ b/cmd/tsidp/depaware.txt
@@ -253,7 +253,7 @@ tailscale.com/cmd/tsidp dependencies: (generated by github.com/tailscale/depawar
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/control/controlclient+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/appc+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
   LW    tailscale.com/util/cmpver                                    from tailscale.com/net/dns+
diff --git a/tsnet/depaware.txt b/tsnet/depaware.txt
index 4817a511a..cf91aa483 100644
--- a/tsnet/depaware.txt
+++ b/tsnet/depaware.txt
@@ -248,7 +248,7 @@ tailscale.com/tsnet dependencies: (generated by github.com/tailscale/depaware)
         tailscale.com/types/views                                    from tailscale.com/appc+
         tailscale.com/util/backoff                                   from tailscale.com/control/controlclient+
         tailscale.com/util/checkchange                               from tailscale.com/ipn/ipnlocal+
-        tailscale.com/util/cibuild                                   from tailscale.com/health
+        tailscale.com/util/cibuild                                   from tailscale.com/health+
         tailscale.com/util/clientmetric                              from tailscale.com/appc+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
   LW    tailscale.com/util/cmpver                                    from tailscale.com/net/dns+
diff --git a/util/eventbus/subscribe.go b/util/eventbus/subscribe.go
index 03d577f27..53253d330 100644
--- a/util/eventbus/subscribe.go
+++ b/util/eventbus/subscribe.go
@@ -7,10 +7,12 @@ import (
 	"context"
 	"fmt"
 	"reflect"
+	"runtime"
 	"sync"
 	"time"
 
 	"tailscale.com/types/logger"
+	"tailscale.com/util/cibuild"
 )
 
 type DeliveredEvent struct {
@@ -329,6 +331,11 @@ func (s *SubscriberFunc[T]) dispatch(ctx context.Context, vals *queue[DeliveredE
 			select {
 			case <-s.slow.C:
 				s.logf("giving up on subscriber for %T after %v at close", t, time.Since(start))
+				if cibuild.On() {
+					all := make([]byte, 2<<20)
+					n := runtime.Stack(all, true)
+					s.logf("goroutine stacks:\n%s", all[:n])
+				}
 			case <-callDone:
 			}
 			return false