src/pkg/rand/rand_test.go | 15 +++++++++++++++

diff --git a/src/pkg/rand/rand_test.go b/src/pkg/rand/rand_test.go
index ae417a9be704b88dbde52cfd2d0642e617e7195a..e0d1da4bb70a7255c4ab0229f6fd5875c4a41e03 100644
--- a/src/pkg/rand/rand_test.go
+++ b/src/pkg/rand/rand_test.go
@@ -312,3 +312,18 @@ 	if i := compareFloat32Slices(fe[0:], testFe); i >= 0 {
 		t.Errorf("fe disagrees at index %v; %v != %v\n", i, fe[i], testFe[i])
 	}
 }
+
+// Benchmarks
+
+func BenchmarkInt63Threadsafe(b *testing.B) {
+	for n := b.N; n > 0; n-- {
+		Int63()
+	}
+}
+
+func BenchmarkInt63Unthreadsafe(b *testing.B) {
+	r := New(NewSource(1));
+	for n := b.N; n > 0; n-- {
+		r.Int63()
+	}
+}