diff --git a/evaluator/evaluator.go b/evaluator/evaluator.go
index 5eb6821c..fe04667b 100644
--- a/evaluator/evaluator.go
+++ b/evaluator/evaluator.go
@@ -1092,11 +1092,16 @@ func evalIndexExpression(node *ast.IndexExpression, env *object.Environment) obj
 }
 
 func evalStringIndexExpression(tok token.Token, array, index object.Object, end object.Object, isRange bool) object.Object {
+	// TODO this gotta be refactored so that
+	// evalStringIndexExpression and evalArrayIndexExpression
+	// reuse most of their code, now it's a bit messy as
+	// the code is duplicated in both places
 	stringObject := array.(*object.String)
 	idx := index.(*object.Number).Int()
-	max := len(stringObject.Value)
+	max := len(stringObject.Value) - 1
 
 	if isRange {
+		max += 1
 		// A range's minimum value is 0
 		if idx < 0 {
 			idx = 0
@@ -1140,6 +1145,7 @@ func evalArrayIndexExpression(tok token.Token, array, index object.Object, end o
 	max := len(arrayObject.Elements) - 1
 
 	if isRange {
+		max += 1
 		// A range's minimum value is 0
 		if idx < 0 {
 			idx = 0
@@ -1153,7 +1159,7 @@ func evalArrayIndexExpression(tok token.Token, array, index object.Object, end o
 			if endIdx.Int() < 0 {
 				max = int(math.Max(float64(max+endIdx.Int()), 0))
 			} else if endIdx.Int() < max {
-				max = endIdx.Int() - 1
+				max = endIdx.Int()
 			}
 		} else if end != NULL {
 			// if the end index is not a number nor null, then we have an error
@@ -1167,7 +1173,7 @@ func evalArrayIndexExpression(tok token.Token, array, index object.Object, end o
 			return &object.Array{Token: tok, Elements: []object.Object{}}
 		}
 
-		return &object.Array{Token: tok, Elements: arrayObject.Elements[idx : max+1]}
+		return &object.Array{Token: tok, Elements: arrayObject.Elements[idx:max]}
 	}
 
 	if idx < 0 || idx > max {
diff --git a/evaluator/evaluator_test.go b/evaluator/evaluator_test.go
index be3fc8b9..7ce10634 100644
--- a/evaluator/evaluator_test.go
+++ b/evaluator/evaluator_test.go
@@ -1390,6 +1390,10 @@ func TestArrayIndexExpressions(t *testing.T) {
 			"a = [1, 2, 3, 4, 5, 6, 7, 8, 9][-10:]; a[0]",
 			1,
 		},
+		{
+			`a = [0,1,2,3,4,5][2:5]; len(a)`,
+			3,
+		},
 	}
 
 	for _, tt := range tests {
@@ -1532,6 +1536,18 @@ func TestStringIndexExpressions(t *testing.T) {
 			`"123"[-10:{}]`,
 			`index ranges can only be numerical: got "{}" (type HASH)`,
 		},
+		{
+			`"123"[-2]`,
+			"",
+		},
+		{
+			`"123"[3]`,
+			"",
+		},
+		{
+			`"123"[0]`,
+			"1",
+		},
 	}
 
 	for _, tt := range tests {