diff --git a/cloud/agent/main.go b/cloud/agent/main.go
index 16d5b17..45c3e52 100644
--- a/cloud/agent/main.go
+++ b/cloud/agent/main.go
@@ -39,7 +39,7 @@
 		}
 		reader, err := lt.Read("", logtree.WithChildren(), logtree.WithStream())
 		if err != nil {
-			panic(fmt.Errorf("could not set up root log reader: %v", err))
+			panic(fmt.Sprintf("could not set up root log reader: %v", err))
 		}
 		go func() {
 			for {
diff --git a/metropolis/node/core/main.go b/metropolis/node/core/main.go
index ba6e9fa..ba760f7 100644
--- a/metropolis/node/core/main.go
+++ b/metropolis/node/core/main.go
@@ -80,7 +80,7 @@
 		}
 		reader, err := lt.Read("", logtree.WithChildren(), logtree.WithStream())
 		if err != nil {
-			panic(fmt.Errorf("could not set up root log reader: %v", err))
+			panic(fmt.Sprintf("could not set up root log reader: %v", err))
 		}
 		c.reader = reader
 		go func() {
diff --git a/metropolis/test/nanoswitch/nanoswitch.go b/metropolis/test/nanoswitch/nanoswitch.go
index 3f4fd93..0bc65bd 100644
--- a/metropolis/test/nanoswitch/nanoswitch.go
+++ b/metropolis/test/nanoswitch/nanoswitch.go
@@ -204,7 +204,7 @@
 	lt := logtree.New()
 	reader, err := lt.Read("", logtree.WithChildren(), logtree.WithStream())
 	if err != nil {
-		panic(fmt.Errorf("could not set up root log reader: %v", err))
+		panic(fmt.Sprintf("could not set up root log reader: %v", err))
 	}
 	go func() {
 		for p := range reader.Stream {