diff --git a/devNotes/twine JS b/devNotes/twine JS
index a39bcc66fed680212a40d71ab96ed9fa7bab3a35..15f1ddc9279d942e2455629ee501424095c6099e 100644
--- a/devNotes/twine JS	
+++ b/devNotes/twine JS	
@@ -8066,7 +8066,7 @@ window.FResult = (function() {
 
 	function calcWorksWithRelativesVanilla(slave) {
 		const fre = getSlave(slave.relationTarget)
-		if (fre !== null && sameAssignmentP(slave, fre)) {
+		if (fre !== undefined && sameAssignmentP(slave, fre)) {
 			V.FResult += 2;
 			if (incest_bonus) V.FResult += 2;
 		}
diff --git a/src/js/fresult.tw b/src/js/fresult.tw
index d803bf94b9c28e8db9732cd8a022c6d57f85b42b..84e571edbf51b4a2390866543750ca62b3ecbe95 100644
--- a/src/js/fresult.tw
+++ b/src/js/fresult.tw
@@ -101,7 +101,7 @@ window.FResult = (function() {
 
 	function calcWorksWithRelativesVanilla(slave) {
 		const fre = getSlave(slave.relationTarget)
-		if (fre !== null && sameAssignmentP(slave, fre)) {
+		if (fre !== undefined && sameAssignmentP(slave, fre)) {
 			V.FResult += 2;
 			if (incest_bonus) V.FResult += 2;
 		}