diff --git a/test/ruby/test_complex.rb b/test/ruby/test_complex.rb
index 3205329a87..5a6d90333e 100644
--- a/test/ruby/test_complex.rb
+++ b/test/ruby/test_complex.rb
@@ -967,6 +967,10 @@ class Complex_Test < Test::Unit::TestCase
       assert_in_delta(1.092, c.real, 0.001)
       assert_in_delta(-0.420, c.imag, 0.001)
 
+      c = CMath.log2(Complex(1, 2))
+      assert_in_delta(1.161, c.real, 0.001)
+      assert_in_delta(1.597, c.imag, 0.001)
+
       c = CMath.log10(Complex(1, 2))
       assert_in_delta(0.349, c.real, 0.001)
       assert_in_delta(0.480, c.imag, 0.001)