diff --git a/d2graph/d2graph.go b/d2graph/d2graph.go
index 56a87b5dc..e916c9b37 100644
--- a/d2graph/d2graph.go
+++ b/d2graph/d2graph.go
@@ -1036,9 +1036,11 @@ func (obj *Object) GetDefaultSize(mtexts []*d2target.MText, ruler *textmeasure.R
 			}
 			maxTypeWidth = go2.Max(maxTypeWidth, typeDims.Width)
 
-			// 60 covers UNQ constraint with padding, 40 for further constraints covers UNQ + space
-			if newWidth := 60 + 40*(len(c.Constraint)-1); newWidth > constraintWidth {
-				constraintWidth = newWidth
+			if l := len(c.Constraint); l > 0 {
+				// 60 covers UNQ constraint with padding, 40 for further constraints covers UNQ + space
+				if newWidth := 60 + 40*(l-1); newWidth > constraintWidth {
+					constraintWidth = newWidth
+				}
 			}
 		}