diff --git a/d2layouts/d2sequence/sequence_diagram.go b/d2layouts/d2sequence/sequence_diagram.go
index 8a61e9e8b..b2cbc5481 100644
--- a/d2layouts/d2sequence/sequence_diagram.go
+++ b/d2layouts/d2sequence/sequence_diagram.go
@@ -476,12 +476,12 @@ func (sd *sequenceDiagram) routeMessages() error {
 		if startCenter := getCenter(message.Src); startCenter != nil {
 			startX = startCenter.X
 		} else {
-			return fmt.Errorf("could not find center of %s", message.Src.AbsID())
+			return fmt.Errorf("could not find center of %s. Is it declared as an actor?", message.Src.ID)
 		}
 		if endCenter := getCenter(message.Dst); endCenter != nil {
 			endX = endCenter.X
 		} else {
-			return fmt.Errorf("could not find center of %s", message.Dst.AbsID())
+			return fmt.Errorf("could not find center of %s. Is it declared as an actor?", message.Dst.ID)
 		}
 		isToDescendant := strings.HasPrefix(message.Dst.AbsID(), message.Src.AbsID()+".")
 		isFromDescendant := strings.HasPrefix(message.Src.AbsID(), message.Dst.AbsID()+".")
@@ -526,7 +526,7 @@ func (sd *sequenceDiagram) routeMessages() error {
 func getCenter(obj *d2graph.Object) *geo.Point {
 	if obj == nil {
 		return nil
-	} else if obj.TopLeft != nil {
+	} else if obj.Box != nil && obj.Box.TopLeft != nil {
 		return obj.Center()
 	}
 	return getCenter(obj.Parent)
diff --git a/e2etests/e2e_test.go b/e2etests/e2e_test.go
index b1ac13cc8..41ad5498d 100644
--- a/e2etests/e2e_test.go
+++ b/e2etests/e2e_test.go
@@ -77,6 +77,7 @@ type testCase struct {
 	mtexts     []*d2target.MText
 	assertions func(t *testing.T, diagram *d2target.Diagram)
 	skip       bool
+	expErr     string
 }
 
 func runa(t *testing.T, tcs []testCase) {
@@ -148,7 +149,14 @@ func run(t *testing.T, tc testCase) {
 			ThemeID:       0,
 			Layout:        layout,
 		})
-		trequire.Nil(t, err)
+
+		if tc.expErr != "" {
+			assert.Error(t, err)
+			assert.ErrorString(t, err, tc.expErr)
+			return
+		} else {
+			assert.Success(t, err)
+		}
 
 		if tc.assertions != nil {
 			t.Run("assertions", func(t *testing.T) {
diff --git a/e2etests/regression_test.go b/e2etests/regression_test.go
index ab5785511..c423daee0 100644
--- a/e2etests/regression_test.go
+++ b/e2etests/regression_test.go
@@ -467,6 +467,21 @@ class2: class without rows {
 }
 `,
 		},
+		{
+			name: "sequence-panic",
+			script: `
+shape: sequence_diagram
+
+a
+
+group: {
+  inner_group: {
+    a -> b
+  }
+}
+`,
+			expErr: "could not find center of b. Is it declared as an actor?",
+		},
 	}
 
 	runa(t, tcs)