diff --git a/bits/62_fxls.js b/bits/62_fxls.js
index b8f9d74..235cdbc 100644
--- a/bits/62_fxls.js
+++ b/bits/62_fxls.js
@@ -811,7 +811,7 @@ function stringify_formula(formula/*Array<any>*/, range, cell/*:any*/, supbooks,
 				break;
 			case 'PtgArea3d': /* 2.5.198.28 TODO */
 				type = f[1][0]; ixti = /*::Number(*/f[1][1]/*::)*/; r = f[1][2];
-				sname = (supbooks && supbooks[1] ? supbooks[1][ixti+1] : "**MISSING**");
+				sname = supbooks && supbooks[1] ? supbooks[1][ixti+1] : (supbooks.SheetNames[ixti] ? supbooks.SheetNames[ixti] : "**MISSING**");
 				stack.push(sname + "!" + encode_range((r/*:any*/)));
 				break;
 			case 'PtgAttrSum': /* 2.5.198.41 */