diff --git a/lib/std/core/builtin.c3 b/lib/std/core/builtin.c3
index 8016bad12..79b82a19b 100644
--- a/lib/std/core/builtin.c3
+++ b/lib/std/core/builtin.c3
@@ -120,17 +120,37 @@ macro enum_by_name($Type, String enum_name) @builtin
 	return SearchResult.MISSING!;
 }
 
-macro bool @expect_true(bool value) @builtin => $$expect(value, true);
-macro bool @expect_false(bool value) @builtin => $$expect(value, false);
+macro bool @likely(bool value, $probability = 1.0) @builtin
+{
+    $if ($probability == 1.0):
+	return $$expect(value, true);
+    $else:
+	return $$expect_with_probability(value, true, $probability);
+    $endif;
+}
+
+macro bool @unlikely(bool value, $probability = 1.0) @builtin
+{
+    $if ($probability == 1.0):
+	return $$expect(value, false);
+    $else:
+	return $$expect_with_probability(value, false, $probability);
+    $endif;
+}
 
 /**
- * @require values::@is_int(value)
+ * @require values::@is_int(value) || values::@is_bool(value)
  * @checked $typeof(value) a = expected
  **/
-macro @expect(value, expected) @builtin
+macro @expect(value, expected, $probability = 1.0) @builtin
 {
+    $if ($probability == 1.0):
 	return $$expect(value, ($typeof(value))expected);
+    $else:
+	return $$expect_with_probability(value, expected, $probability);
+    $endif;
 }
+
 /**
  * Locality for prefetch, levels 0 - 3, corresponding
  * to "extremely local" to "no locality"
diff --git a/lib/std/core/types.c3 b/lib/std/core/types.c3
index 0f866f9b9..682c80a11 100644
--- a/lib/std/core/types.c3
+++ b/lib/std/core/types.c3
@@ -123,6 +123,7 @@ macro bool is_subarray_convertable($Type)
 	$endswitch;
 }
 
+macro bool is_bool($Type) => $Type.kindof == TypeKind.BOOL;
 macro bool is_int($Type) => $Type.kindof == TypeKind.SIGNED_INT || $Type.kindof == TypeKind.UNSIGNED_INT;
 
 macro bool is_intlike($Type)
diff --git a/lib/std/core/values.c3 b/lib/std/core/values.c3
index dadf46dcb..021050ef0 100644
--- a/lib/std/core/values.c3
+++ b/lib/std/core/values.c3
@@ -2,6 +2,7 @@ module std::core::values;
 
 macro TypeKind @typekind(#value) @builtin => $typeof(#value).kindof;
 macro bool @typeis(#value, $Type) @builtin => $typeof(#value).typeid == $Type.typeid;
+macro bool @is_bool(#value) => types::is_bool($typeof(#value));
 macro bool @is_int(#value) => types::is_int($typeof(#value));
 macro bool @convertable_to(#a, #b) => $checks($typeof(#b) x = #a);
 macro bool @is_floatlike(#value) => types::is_floatlike($typeof(#value));
diff --git a/test/unit/stdlib/macros/core_builtins.c3 b/test/unit/stdlib/macros/core_builtins.c3
new file mode 100644
index 000000000..a67a1e897
--- /dev/null
+++ b/test/unit/stdlib/macros/core_builtins.c3
@@ -0,0 +1,23 @@
+module core_builtin_tests;
+
+fn void! test_likely() @test
+{
+	assert(@likely(2 > 1));
+	assert(@likely(2 > 1, 0.5));
+}
+
+fn void! test_unlikely() @test
+{
+	assert(@unlikely(2 < 1));
+	assert(@unlikely(2 < 1, 0.5));
+}
+
+fn void! test_expect() @test
+{
+	assert(@expect(2 > 1, true));
+	assert(@expect(2 < 1, false));
+
+	assert(@expect(2 > 1, true, 0.5));
+	assert(@expect(2 < 1, false, 0.5));
+}
+