diff --git a/manager/dirty.go b/manager/dirty.go
index c989ec2c86..2f3460436f 100644
--- a/manager/dirty.go
+++ b/manager/dirty.go
@@ -1,6 +1,7 @@
 package manager
 
 import (
+	"fmt"
 	"reflect"
 
 	"github.com/docker/swarmkit/api"
@@ -45,7 +46,7 @@ func (m *Manager) IsStateDirty() (bool, error) {
 		field := val.Field(i)
 		structField := val.Type().Field(i)
 		if structField.Type.Kind() != reflect.Slice {
-			panic("unexpected field type in StoreSnapshot")
+			panic(fmt.Sprintf("unexpected field type in StoreSnapshot: %s (type %v)", structField.Name, structField.Type.Kind()))
 		}
 		if structField.Name != "Nodes" && structField.Name != "Clusters" && structField.Name != "Networks" && field.Len() != 0 {
 			// One of the other data types has an entry
diff --git a/protobuf/plugin/deepcopy/test/deepcopypb_test.go b/protobuf/plugin/deepcopy/test/deepcopypb_test.go
index f542bb67d0..e1c2d168c7 100644
--- a/protobuf/plugin/deepcopy/test/deepcopypb_test.go
+++ b/protobuf/plugin/deepcopy/test/deepcopypb_test.go
@@ -4,15 +4,16 @@
 package test
 
 import (
-	fmt "fmt"
+	"fmt"
+	"math"
+	math_rand "math/rand"
+	"testing"
+	"time"
+
 	_ "github.com/gogo/protobuf/gogoproto"
 	github_com_gogo_protobuf_jsonpb "github.com/gogo/protobuf/jsonpb"
+	"github.com/gogo/protobuf/proto"
 	github_com_gogo_protobuf_proto "github.com/gogo/protobuf/proto"
-	proto "github.com/gogo/protobuf/proto"
-	math "math"
-	math_rand "math/rand"
-	testing "testing"
-	time "time"
 )
 
 // Reference imports to suppress errors if they are not otherwise used.