diff --git a/ext/enumerable/statistics/extension/statistics.c b/ext/enumerable/statistics/extension/statistics.c
index 3006fdf..df93548 100644
--- a/ext/enumerable/statistics/extension/statistics.c
+++ b/ext/enumerable/statistics/extension/statistics.c
@@ -163,7 +163,7 @@ complex_add(VALUE self, VALUE other)
 
     real = f_add(RCOMPLEX(self)->real, other);
 
-    return complex_new(CLASS_OF(self), real, RCOMPLEX(other)->imag);
+    return complex_new(CLASS_OF(self), real, RCOMPLEX(self)->imag);
   }
   return rb_num_coerce_bin(self, other, idPLUS);
 }
diff --git a/spec/array_spec.rb b/spec/array_spec.rb
index 3759a6a..0a580b6 100644
--- a/spec/array_spec.rb
+++ b/spec/array_spec.rb
@@ -3,6 +3,12 @@
 require 'delegate'
 
 RSpec.describe Array do
+  describe '#sum' do
+    it 'sums with a complex init' do
+      expect([1, 2, 3].sum(Complex(1, 2))).to eq(Complex(7, 2))
+    end
+  end
+
   describe '#mean' do
     let(:ary) { [] }
     let(:block) { nil }