diff --git a/operator-index.go b/operator-index.go
index c833a23..af91069 100644
--- a/operator-index.go
+++ b/operator-index.go
@@ -40,11 +40,14 @@ func verifyRange(indexTerm *term, indexList *ListType, maxValue int) (startIndex
 	v, _ := ((*indexList)[0]).(*intPair)
 	startIndex = v.a
 	endIndex = v.b
+	if endIndex == ConstLastIndex {
+		endIndex = maxValue
+	}
 	if startIndex < 0 && startIndex >= -maxValue {
 		startIndex = maxValue + startIndex
 	}
 	if endIndex < 0 && endIndex >= -maxValue {
-		endIndex = maxValue + endIndex + 1
+		endIndex = maxValue + endIndex
 	}
 	if startIndex < 0 || startIndex > maxValue {
 		err = indexTerm.Errorf("range start-index %d is out of bounds", startIndex)