diff --git a/lib/std/core/allocators/tracking_allocator.c3 b/lib/std/core/allocators/tracking_allocator.c3
index 79877c57e..a43ea9c7c 100644
--- a/lib/std/core/allocators/tracking_allocator.c3
+++ b/lib/std/core/allocators/tracking_allocator.c3
@@ -113,8 +113,14 @@ fn void TrackingAllocator.clear(&self)
 	self.map.clear();
 }
 
+fn bool TrackingAllocator.has_leaks(&self)
+{
+	return self.map.len() > 0;
+}
+
 fn void TrackingAllocator.print_report(&self) => self.fprint_report(io::stdout())!!;
 
+
 fn void! TrackingAllocator.fprint_report(&self, OutStream out) => @pool()
 {
 	usz total = 0;
diff --git a/lib/std/core/runtime_test.c3 b/lib/std/core/runtime_test.c3
index d3b00c678..cc0b23bad 100644
--- a/lib/std/core/runtime_test.c3
+++ b/lib/std/core/runtime_test.c3
@@ -260,21 +260,31 @@ fn bool run_tests(String[] args, TestUnit[] tests) @private
 		if (libc::setjmp(&context.buf) == 0)
 		{
 			mute_output();
-			$if(!$$OLD_TEST):
-				unit.func();
-			$else
-				if (catch err = unit.func())
-				{
-					io::printf("[FAIL] Failed due to: %s", err);
-					continue;
-				}
-			$endif
+			TrackingAllocator mem;
+			mem.init(allocator::heap());
+			bool has_leaks;
+			mem::@scoped(&mem)
+			{
+				$if(!$$OLD_TEST):
+					unit.func();
+				$else
+					if (catch err = unit.func())
+					{
+						io::printf("[FAIL] Failed due to: %s", err);
+						continue;
+					}
+				$endif
+				has_leaks = mem.has_leaks();
+			};
+			mem.free();
 			unmute_output(false); // all good, discard output
 
-
-			io::printfn(test_context.has_ansi_codes ? "[\e[0;32mPASS\e[0m]" : "[PASS]");
+			io::printf(test_context.has_ansi_codes ? "[\e[0;32mPASS\e[0m]" : "[PASS]");
 			tests_passed++;
 
+			if (has_leaks) io::print(" LEAKS!");
+			io::printn();
+
 			if (test_context.teardown_fn)
 			{
 				test_context.teardown_fn();
diff --git a/test/unit/regression/liveness_any.c3 b/test/unit/regression/liveness_any.c3
index 8ae500eb1..bd271ca61 100644
--- a/test/unit/regression/liveness_any.c3
+++ b/test/unit/regression/liveness_any.c3
@@ -17,4 +17,6 @@ fn void reflect_test() @test
 {
 	TestProto b = mem::alloc(Test);
 	b.tesT();
+	defer free(b);
+
 }
\ No newline at end of file
diff --git a/test/unit/regression/lvalue_handling.c3 b/test/unit/regression/lvalue_handling.c3
index e54482245..a07be6a71 100644
--- a/test/unit/regression/lvalue_handling.c3
+++ b/test/unit/regression/lvalue_handling.c3
@@ -8,6 +8,8 @@ def IntList = List(<Foo>);
 fn void subscript_overload() @test
 {
 	IntList x;
+	defer x.free();
+
 	x.push({ 3 });
 	int* a = &x[0].a;
 	assert(*a == 3);
diff --git a/test/unit/stdlib/atomic.c3 b/test/unit/stdlib/atomic.c3
index b7ba45bb1..3842ebd33 100644
--- a/test/unit/stdlib/atomic.c3
+++ b/test/unit/stdlib/atomic.c3
@@ -5,7 +5,7 @@ import std::atomic;
 uint a;
 float fa;
 
-fn void add() @test
+fn void add() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	a = 0;
@@ -42,7 +42,7 @@ fn void add() @test
 	assert(a == ts.len * 10 * 5, "Threads returned %d, expected %d", a, ts.len * 10 * 5);
 }
 
-fn void sub() @test
+fn void sub() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	a = ts.len * 10 * 5;
@@ -79,7 +79,7 @@ fn void sub() @test
 	assert(a == 0, "Threads returned %d, expected %d", a, 0);
 }
 
-fn void div() @test
+fn void div() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[8] ts;
 	a = 8 * 8 * 8 * 8 * 8 * 8 * 8 * 8 * 8;
@@ -98,7 +98,7 @@ fn void div() @test
 	assert(a == 8, "Threads returned %d, expected %d", a, 8);
 }
 
-fn void max() @test
+fn void max() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	a = 0;
@@ -134,7 +134,7 @@ fn void max() @test
 	assert(a == 5, "Threads returned %d, expected %d", a, 5);
 }
 
-fn void min() @test
+fn void min() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	a = 10;
@@ -170,7 +170,7 @@ fn void min() @test
 	assert(a == 0, "Threads returned %d, expected %d", a, 0);
 }
 
-fn void fadd() @test
+fn void fadd() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	fa = 0;
@@ -207,7 +207,7 @@ fn void fadd() @test
 	assert(fa == ts.len * 10 * 0.5, "Threads returned %f, expected %f", fa, ts.len * 10 * 0.5);
 }
 
-fn void fsub() @test
+fn void fsub() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	fa = ts.len * 10 * 0.5;
diff --git a/test/unit/stdlib/atomic_types.c3 b/test/unit/stdlib/atomic_types.c3
index 8c9c434c5..0cd721855 100644
--- a/test/unit/stdlib/atomic_types.c3
+++ b/test/unit/stdlib/atomic_types.c3
@@ -7,7 +7,7 @@ def AtomicFloat = Atomic(<float>);
 AtomicUint a;
 AtomicFloat fa;
 
-fn void add() @test
+fn void add() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	a.store(0);
@@ -44,7 +44,7 @@ fn void add() @test
 	assert(a.load() == ts.len * 10 * 5, "Threads returned %d, expected %d", a.load(), ts.len * 10 * 5);
 }
 
-fn void sub() @test
+fn void sub() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	a.store(ts.len * 10 * 5);
@@ -81,7 +81,7 @@ fn void sub() @test
 	assert(a.load() == 0, "Threads returned %d, expected %d", a.load(), 0);
 }
 
-fn void fadd() @test
+fn void fadd() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	fa.store(0);
@@ -118,7 +118,7 @@ fn void fadd() @test
 	assert(fa.load() == ts.len * 10 * 0.5, "Threads returned %f, expected %f", fa.load(), ts.len * 10 * 0.5);
 }
 
-fn void fsub() @test
+fn void fsub() @test => mem::@scoped(&allocator::LIBC_ALLOCATOR)
 {
 	Thread[100] ts;
 	fa.store(ts.len * 10 * 0.5);
diff --git a/test/unit/stdlib/collections/linkedlist.c3 b/test/unit/stdlib/collections/linkedlist.c3
index 2ce4be4fc..d0c94c195 100644
--- a/test/unit/stdlib/collections/linkedlist.c3
+++ b/test/unit/stdlib/collections/linkedlist.c3
@@ -6,6 +6,7 @@ def IntList = LinkedList(<int>);
 fn void test_push_front()
 {
 	IntList list;
+	defer list.free();
 	list.push_front(23);
 	assert(list.len() == 1);
 	assert(list.first()!! == 23);
@@ -14,11 +15,13 @@ fn void test_push_front()
 	assert(list.len() == 2);
 	assert(list.last()!! == 23);
 	assert(list.first()!! == 55);
+
 }
 
 fn void test_push()
 {
 	IntList list;
+	defer list.free();
 	list.push(23);
 	assert(list.len() == 1);
 	assert(list.first()!! == 23);
@@ -32,6 +35,7 @@ fn void test_push()
 fn void test_get()
 {
 	IntList list;
+	defer list.free();
 	list.push(23);
 	list.push(55);
 	list.push(-3);
@@ -43,6 +47,7 @@ fn void test_get()
 fn void test_insert()
 {
 	IntList list;
+	defer list.free();
 	list.push(-3);
 	list.push(55);
 	list.push(23);
@@ -62,6 +67,7 @@ fn void test_insert()
 fn void test_set()
 {
 	IntList list;
+	defer list.free();
     list.push(-3);
 	list.push(55);
 	list.push(23);
@@ -74,6 +80,7 @@ fn void test_set()
 fn void test_remove_at()
 {
 	IntList list;
+	defer list.free();
 	for (int i = 0; i < 10; i++) list.push(i);
 	list.remove_at(0);
 	list.remove_at(1);
@@ -88,6 +95,7 @@ fn void test_remove_at()
 fn void test_remove()
 {
 	IntList list;
+	defer list.free();
 	list.push(2);
 	for (int i = 0; i < 10; i++) list.push(5);
 	list.push(2);
@@ -98,6 +106,7 @@ fn void test_remove()
 fn void test_remove_first_match()
 {
 	IntList list;
+	defer list.free();
 	list.push(23);
 	list.push(55);
 	list.push(-3);
@@ -126,6 +135,7 @@ fn void test_remove_first_match()
 fn void test_remove_last_match()
 {
 	IntList list;
+	defer list.free();
 	list.push(23);
 	list.push(55);
 	list.push(-3);
@@ -154,6 +164,7 @@ fn void test_remove_last_match()
 fn void test_pop()
 {
 	IntList list;
+	defer list.free();
 	list.push(23);
 	list.push(55);
 	list.push(-3);
@@ -178,6 +189,7 @@ fn void test_pop()
 fn void test_remove_last()
 {
 	IntList list;
+	defer list.free();
 	list.push(23);
 	list.push(55);
 	list.push(-3);
@@ -202,6 +214,7 @@ fn void test_remove_last()
 fn void test_remove_first()
 {
 	IntList list;
+	defer list.free();
 	list.push(23);
 	list.push(55);
 	list.push(-3);
diff --git a/test/unit/stdlib/collections/list.c3 b/test/unit/stdlib/collections/list.c3
index 91a2bcd7f..6a31585e1 100644
--- a/test/unit/stdlib/collections/list.c3
+++ b/test/unit/stdlib/collections/list.c3
@@ -13,6 +13,8 @@ def OveralignList = List(<Overalign>);
 fn void overaligned_type()
 {
 	OveralignList l;
+	defer l.free();
+
 	Overalign y;
 	for (int i = 0; i < 1000; i++) l.push(y);
 	assert((usz)l.get_ref(2) - (usz)l.get_ref(1) == Overalign.sizeof);
@@ -22,6 +24,8 @@ fn void overaligned_type()
 fn void delete_contains_index()
 {
 	IntList test;
+	defer test.free();
+
 	test.add_array({ 1, 2 });
 	assert(test.contains(1));
 	assert(test.contains(2));
@@ -51,6 +55,7 @@ fn void delete_contains_index()
 fn void compact()
 {
 	PtrList test;
+	defer test.free();
 	test.add_array({ null, &test });
 	assert(test.compact_count() == 1);
 	test.push(null);
@@ -64,6 +69,8 @@ fn void compact()
 fn void reverse()
 {
 	IntList test;
+	defer test.free();
+
 	test.reverse();
 	test.add_array({ 1, 2 });
 	test.push(3);
@@ -79,6 +86,7 @@ fn void reverse()
 fn void remove_if()
 {
 	IntList test;
+	defer test.free();
 	usz removed;
 
 	test.add_array({ 1, 11, 2, 10, 20 });
@@ -96,6 +104,7 @@ fn void remove_if()
 fn void init_with_array()
 {
 	IntList foo;
+	defer foo.free();
 	foo.new_init_with_array({ 1, 2, 3});
 	assert(foo.len() == 3);
 	assert(foo[2] == 3);
@@ -112,6 +121,7 @@ fn void init_with_temp_array()
 fn void remove_using_test()
 {
 	IntList test;
+	defer test.free();
 	usz removed;
 
 	test.add_array({ 1, 11, 2, 10, 20 });
@@ -129,6 +139,7 @@ fn void remove_using_test()
 fn void retain_if()
 {
 	IntList test;
+	defer test.free();
 	usz removed;
 
 	test.add_array({ 1, 11, 2, 10, 20 });
@@ -146,6 +157,7 @@ fn void retain_if()
 fn void retain_using_test()
 {
 	IntList test;
+	defer test.free();
 	usz removed;
 
 	test.add_array({ 1, 11, 2, 10, 20 });
diff --git a/test/unit/stdlib/collections/object.c3 b/test/unit/stdlib/collections/object.c3
index 5cb4b614e..35053fc36 100644
--- a/test/unit/stdlib/collections/object.c3
+++ b/test/unit/stdlib/collections/object.c3
@@ -4,6 +4,8 @@ import std::collections::object;
 fn void test_general()
 {
 	Object* root = object::new_obj(allocator::heap());
+	defer root.free();
+
 	root.set("foo", 1);
 	root.set("bar", "baz");
 	assert(root.get_int("foo")!! == 1);
diff --git a/test/unit/stdlib/collections/priorityqueue.c3 b/test/unit/stdlib/collections/priorityqueue.c3
index a95fff150..44bd0c7bc 100644
--- a/test/unit/stdlib/collections/priorityqueue.c3
+++ b/test/unit/stdlib/collections/priorityqueue.c3
@@ -7,6 +7,8 @@ def Queue = PriorityQueue(<int>);
 fn void priorityqueue()
 {
     Queue q;
+	defer q.free();
+
     assert(q.is_empty());
 
     q.push(1);
@@ -35,6 +37,7 @@ def QueueMax = PriorityQueueMax(<int>);
 fn void priorityqueue_max()
 {
     QueueMax q;
+	defer q.free();
     assert(q.is_empty());
 
     q.push(1);
diff --git a/test/unit/stdlib/compression/qoi.c3 b/test/unit/stdlib/compression/qoi.c3
index bf027e5bd..c617edc87 100644
--- a/test/unit/stdlib/compression/qoi.c3
+++ b/test/unit/stdlib/compression/qoi.c3
@@ -30,5 +30,8 @@ fn void test_qoi_all()
 
         // cleanup
         file::delete("unittest.qoi")!!;
+        free(encoded);
+        free(decoded);
+        free(read);
     };
 }
diff --git a/test/unit/stdlib/core/array.c3 b/test/unit/stdlib/core/array.c3
index 03d92b252..e356bed5b 100644
--- a/test/unit/stdlib/core/array.c3
+++ b/test/unit/stdlib/core/array.c3
@@ -21,11 +21,12 @@ fn void find_subarray()
 fn void concat()
 {
 	int[3] a = { 1, 2, 3 };
-	(void)array::concat_new(a, a);
-	(void)array::concat_new(a[..], a[..]);
-	(void)array::concat_new(a[:0], a[:0]);
-	(void)array::concat_new(int[2] { 1, 2 }, a[:0]);
-	(void)array::concat_new(a[:0], int[2] { 1, 2 });
+	free(array::concat_new(a, a));
+	free(array::concat_new(a[..], a[..]));
+	free(array::concat_new(a[:0], a[:0]));
+	free(array::concat_new(int[2] { 1, 2 }, a[:0]));
+	free(array::concat_new(a[:0], int[2] { 1, 2 }));
 	int[] c = array::concat_new(a[1..2], a);
+	defer free(c);
 	assert (c == int[]{ 2, 3, 1, 2, 3 });
 }
diff --git a/test/unit/stdlib/io/printf.c3 b/test/unit/stdlib/io/printf.c3
index d52373019..9b51a066f 100644
--- a/test/unit/stdlib/io/printf.c3
+++ b/test/unit/stdlib/io/printf.c3
@@ -5,14 +5,19 @@ fn void printf_int()
 	String s;
 	s = string::new_format("[%-10d]", 78);
 	assert(s == "[78        ]");
+	free(s);
 	s = string::new_format("[%10d]", 78);
 	assert(s == "[        78]");
+	free(s);
 	s = string::new_format("[%010d]", 78);
 	assert(s == "[0000000078]");
+	free(s);
 	s = string::new_format("[%+10d]", 78);
 	assert(s == "[       +78]");
+	free(s);
 	s = string::new_format("[%-+10d]", 78);
 	assert(s == "[+78       ]");
+	free(s);
 }
 
 fn void printf_a()
@@ -20,51 +25,69 @@ fn void printf_a()
 	String s;
 	s = string::new_format("%08.2a", 234.125);
 	assert(s == "0x1.d4p+7", "got '%s'; want '0x1.d4p+7'", s);
+	free(s);
 	s = string::new_format("%a", 234.125);
 	assert(s == "0x1.d44p+7", "got '%s'; want '0x1.d44p+7'", s);
+	free(s);
 	s = string::new_format("%A", 234.125);
 	assert(s == "0X1.D44P+7", "got '%s'; want '0X1.D44P+7'", s);
+	free(s);
 	s = string::new_format("%20a", 234.125);
 	assert(s == "          0x1.d44p+7", "got '%s'; want '          0x1.d44p+7'", s);
+	free(s);
 	s = string::new_format("%-20a", 234.125);
 	assert(s == "0x1.d44p+7          ", "got '%s'; want '0x1.d44p+7          '", s);
+	free(s);
 	s = string::new_format("%-20s", "hello world");
 	assert(s == "hello world         ", "got '%s'; want 'hello world         '", s);
+	free(s);
 	s = string::new_format("%20s", "hello world");
 	assert(s == "         hello world", "got '%s'; want '         hello world'", s);
+	free(s);
 
 	String str = "hello!";
 	s = string::new_format("%-20s", str);
 	assert(s == "hello!              ", "got '%s'; want 'hello!              '", s);
+	free(s);
 	s = string::new_format("%20s", str);
 	assert(s == "              hello!", "got '%s'; want '              hello!'", s);
+	free(s);
 
 	int[2] a = { 12, 23 };
 	s = string::new_format("%-20s", a);
 	assert(s == "[12, 23]            ", "got '%s'; want '[12, 23]            '", s);
+	free(s);
 	s = string::new_format("%20s", a);
 	assert(s == "            [12, 23]", "got '%s'; want '            [12, 23]'", s);
+	free(s);
 
 	s = string::new_format("%-20s", a[..]);
 	assert(s == "[12, 23]            ", "got '%s'; want '[12, 23]            '", s);
+	free(s);
 	s = string::new_format("%20s", a[..]);
 	assert(s == "            [12, 23]", "got '%s'; want '            [12, 23]'", s);
+	free(s);
 
 	float[2] f = { 12.0, 23.0 };
 	s = string::new_format("%-24s", f);
 	assert(s == "[12.000000, 23.000000]  ", "got '%s'; want '[12.000000, 23.000000]  '", s);
+	free(s);
 	s = string::new_format("%24s", f);
 	assert(s == "  [12.000000, 23.000000]", "got '%s'; want '  [12.000000, 23.000000]'", s);
+	free(s);
 
 	int[<2>] vec = { 12, 23 };
 	s = string::new_format("%-20s", vec);
 	assert(s == "[<12, 23>]          ", "got '%s'; want '[<12, 23>]          '", s);
+	free(s);
 	s = string::new_format("%20s", vec);
 	assert(s == "          [<12, 23>]", "got '%s'; want '          [<12, 23>]'", s);
+	free(s);
 
 	String ss = "hello world";
 	s = string::new_format("%.4s %.5s", ss, ss);
 	assert(s == "hell hello", "got '%s'; want 'hell hello'", s);
+	free(s);
 }
 
 enum PrintfTest : ushort
@@ -79,11 +102,15 @@ fn void printf_enum()
 
 	s = string::new_format("%s", PrintfTest.ENUMA);
 	assert(s == "ENUMA", "got '%s'; want 'ENUMA'", s);
+	free(s);
 	s = string::new_format("%s", PrintfTest.ENUMB);
 	assert(s == "ENUMB", "got '%s'; want 'ENUMB'", s);
+	free(s);
 
 	s = string::new_format("%d", PrintfTest.ENUMA);
 	assert(s == "0", "got '%s'; want '0'", s);
+	free(s);
 	s = string::new_format("%d", PrintfTest.ENUMB);
 	assert(s == "1", "got '%s'; want '1'", s);
+	free(s);
 }
\ No newline at end of file
diff --git a/test/unit/stdlib/net/inetaddr.c3 b/test/unit/stdlib/net/inetaddr.c3
index 76f0e1b74..6c8572302 100644
--- a/test/unit/stdlib/net/inetaddr.c3
+++ b/test/unit/stdlib/net/inetaddr.c3
@@ -12,20 +12,21 @@ fn void test_ipv4()
 fn void test_ipv4_to_string()
 {
 	InetAddress a = net::ipv4_from_str("127.0.0.1")!!;
-	assert(a.to_new_string() == "127.0.0.1");
+	assert(a.to_new_string(allocator::temp()) == "127.0.0.1");
 }
 
 fn void test_ipv6_to_string()
 {
 	InetAddress a = net::ipv6_from_str("2001:db8::2:1")!!;
-	a.to_new_string();
-	assert(a.to_new_string() == "2001:0db8:0000:0000:0000:0000:0002:0001");
-	assert(net::ipv6_from_str("2001:db8::1").to_new_string()!! == "2001:0db8:0000:0000:0000:0000:0000:0001");
-	assert(net::ipv6_from_str("::1").to_new_string()!! == "0000:0000:0000:0000:0000:0000:0000:0001");
-	assert(net::ipv6_from_str("2001::1").to_new_string()!! == "2001:0000:0000:0000:0000:0000:0000:0001");
-	assert(net::ipv6_from_str("2001:db8:1234::").to_new_string()!! == "2001:0db8:1234:0000:0000:0000:0000:0000");
-	assert(net::ipv6_from_str("2001::").to_new_string()!! == "2001:0000:0000:0000:0000:0000:0000:0000");
-	assert(net::ipv6_from_str("::").to_new_string()!! == "0000:0000:0000:0000:0000:0000:0000:0000");
+	free(a.to_new_string());
+
+	assert(a.to_new_string(allocator::temp()) == "2001:0db8:0000:0000:0000:0000:0002:0001");
+	assert(net::ipv6_from_str("2001:db8::1").to_new_string(allocator::temp())!! == "2001:0db8:0000:0000:0000:0000:0000:0001");
+	assert(net::ipv6_from_str("::1").to_new_string(allocator::temp())!! == "0000:0000:0000:0000:0000:0000:0000:0001");
+	assert(net::ipv6_from_str("2001::1").to_new_string(allocator::temp())!! == "2001:0000:0000:0000:0000:0000:0000:0001");
+	assert(net::ipv6_from_str("2001:db8:1234::").to_new_string(allocator::temp())!! == "2001:0db8:1234:0000:0000:0000:0000:0000");
+	assert(net::ipv6_from_str("2001::").to_new_string(allocator::temp())!! == "2001:0000:0000:0000:0000:0000:0000:0000");
+	assert(net::ipv6_from_str("::").to_new_string(allocator::temp())!! == "0000:0000:0000:0000:0000:0000:0000:0000");
 }
 
 fn void test_ipv4_parse()
diff --git a/test/unit/stdlib/os/env.c3 b/test/unit/stdlib/os/env.c3
index 34234b770..ae927b9a3 100644
--- a/test/unit/stdlib/os/env.c3
+++ b/test/unit/stdlib/os/env.c3
@@ -8,7 +8,7 @@ module std::os::env @test;
  	env::set_var(NAME, VALUE);
  	String v = env::get_var(NAME)!!;
  	assert(v == VALUE, "got %s; want %s", v, VALUE);
-
+	free(v);
  	env::clear_var(NAME);
  	if (try env::get_var(NAME))
  	{
diff --git a/test/unit/stdlib/time/format.c3 b/test/unit/stdlib/time/format.c3
index 310078719..0c07fd62c 100644
--- a/test/unit/stdlib/time/format.c3
+++ b/test/unit/stdlib/time/format.c3
@@ -28,6 +28,7 @@ fn void test_with_tz()
 	foreach (test : tests)
 	{
 		String candidate = test.first.new_format(test.second);
+		defer free(candidate);
 		assert(candidate == test.third, "got: '%s', expected: '%s'", candidate, test.third);
 	}
 }
@@ -44,6 +45,7 @@ fn void test_without_tz()
 	foreach (test : tests)
 	{
 		String candidate = test.first.new_format(test.second);
+		defer free(candidate);
 		assert(candidate == test.third, "got: '%s', expected: '%s'", candidate, test.third);
 	}
 }