diff --git a/tests/programs/len.q b/tests/programs/len.q
new file mode 100644
index 0000000..5efdfc7
--- /dev/null
+++ b/tests/programs/len.q
@@ -0,0 +1,14 @@
+import mem
+
+main() {
+	a := mem.alloc(16)
+	assert len(a) == 16
+	mem.free(a)
+
+	assert len("H") == 1
+	assert len("He") == 2
+	assert len("Hel") == 3
+	assert len("Hell") == 4
+	assert len("Hello") == 5
+	assert len("日本") == 6
+}
\ No newline at end of file
diff --git a/tests/programs_test.go b/tests/programs_test.go
index 675548b..d5a1eca 100644
--- a/tests/programs_test.go
+++ b/tests/programs_test.go
@@ -62,6 +62,7 @@ var programs = []struct {
 	{"memory-free", "", "", 0},
 	{"out-of-memory", "", "", 0},
 	{"struct", "", "", 0},
+	{"len", "", "", 0},
 }
 
 func TestPrograms(t *testing.T) {