diff --git a/vlib/builtin/string.v b/vlib/builtin/string.v
index d15247c292..c4154996d7 100644
--- a/vlib/builtin/string.v
+++ b/vlib/builtin/string.v
@@ -183,6 +183,11 @@ pub fn (s string) replace(rep string, with string) string {
 	// TODO PERF Allocating ints is expensive. Should be a stack array
 	// Get locations of all reps within this string
 	mut idxs := []int{}
+	defer  {
+		unsafe {
+			idxs.free()
+		}
+	}
 	mut idx := 0
 	for {
 		idx = s.index_after(rep, idx)
diff --git a/vlib/v/tests/valgrind/1.strings_and_arrays.v b/vlib/v/tests/valgrind/1.strings_and_arrays.v
index 77e427afed..71bd76aa94 100644
--- a/vlib/v/tests/valgrind/1.strings_and_arrays.v
+++ b/vlib/v/tests/valgrind/1.strings_and_arrays.v
@@ -61,12 +61,16 @@ fn str_inter() {
 }
 
 fn str_replace() {
-	s := 'hello world'
+	mut s := 'hello world'
+	s = s.replace('hello', 'hi')
+	println(s)
+	/*
 	r := s.replace('hello', 'hi')
 	cloned := s.replace('hello', 'hi').clone()
 	cloned2 := r.clone()
 	println(s)
 	println(r)
+	*/
 }
 
 fn reassign_str() {
@@ -154,7 +158,7 @@ fn main() {
 	reassign_str()
 	optional_str()
 	optional_return()
-	// str_replace()
+	str_replace()
 	if_cond()
 	addition_with_tmp_expr()
 	println('end')