diff --git a/helper/schema/resource_data.go b/helper/schema/resource_data.go
index 3e728389d..cdc0d82d2 100644
--- a/helper/schema/resource_data.go
+++ b/helper/schema/resource_data.go
@@ -349,10 +349,12 @@ func (d *ResourceData) getSet(
 	var indexMap map[int]int
 	if len(parts) > 0 {
 		indexMap = make(map[int]int)
+	}
 
-		// Build the set from all the items using the given hash code
-		for i, v := range list {
-			code := s.add(v)
+	// Build the set from all the items using the given hash code
+	for i, v := range list {
+		code := s.add(v)
+		if indexMap != nil {
 			indexMap[code] = i
 		}
 	}