diff --git a/CHANGELOG.md b/CHANGELOG.md
index ed0e5434583d..5054b87ec85d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ Compatibility:
 * `Errno` constants with the same `errno` number are now the same class.
 * Implement `Enumerable#tally` and `Enumerable#filter_map` (#2144 and #2152, @LillianZ).
 * Implement `Range#minmax`.
+* Implement `Complex#<=>` (#2004, @ssnickolay).
 
 Performance:
 
diff --git a/spec/tags/core/complex/comparision_tags.txt b/spec/tags/core/complex/comparision_tags.txt
deleted file mode 100644
index c9f13ac819cb..000000000000
--- a/spec/tags/core/complex/comparision_tags.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-fails:Complex#<=> returns nil if either self or argument has imaginary part
-fails:Complex#<=> returns nil if argument is not numeric
-fails:Complex#<=> returns 0, 1, or -1 if self and argument do not have imaginary part
diff --git a/src/main/ruby/truffleruby/core/complex.rb b/src/main/ruby/truffleruby/core/complex.rb
index 35e306f7b729..cdcfadd8d580 100644
--- a/src/main/ruby/truffleruby/core/complex.rb
+++ b/src/main/ruby/truffleruby/core/complex.rb
@@ -36,7 +36,7 @@
 
 class Complex < Numeric
 
-  undef_method :%, :<, :<=, :<=>, :>, :>=, :between?, :clamp, # comparable
+  undef_method :%, :<, :<=, :>, :>=, :between?, :clamp, # comparable
                :div, :divmod, :floor, :ceil, :modulo, :remainder,
                :round, :step, :truncate, :i, :negative?, :positive?
 
@@ -373,6 +373,16 @@ def marshal_load(ary)
     self
   end
 
+  def <=>(other)
+    if imag == 0 && other.kind_of?(Numeric)
+      if other.kind_of?(Complex) && other.imag == 0
+        real <=> other.real
+      elsif other.real?
+        real <=> other
+      end
+    end
+  end
+
   I = Complex(0, 1)
 
 end
diff --git a/test/mri/excludes/Complex_Test.rb b/test/mri/excludes/Complex_Test.rb
index 08224e700937..fa44cc4489db 100644
--- a/test/mri/excludes/Complex_Test.rb
+++ b/test/mri/excludes/Complex_Test.rb
@@ -16,4 +16,3 @@
 exclude :test_rationalize, "needs investigation"
 exclude :test_Complex_with_invalid_exception, "needs investigation"
 exclude :test_conv, "needs investigation"
-exclude :test_cmp, "needs investigation"