diff --git a/lib/fiddle/struct.rb b/lib/fiddle/struct.rb
index a766eba8..0e77a333 100644
--- a/lib/fiddle/struct.rb
+++ b/lib/fiddle/struct.rb
@@ -9,10 +9,24 @@ class CStruct
     include Enumerable
 
     # accessor to Fiddle::CStructEntity
-    def CStruct.entity_class
+    def self.entity_class
       CStructEntity
     end
 
+    def self.malloc(func=nil, &block)
+      if block
+        entity_class.malloc(types, func, size) do |entity|
+          block.call(new(entity))
+        end
+      else
+        new(entity_class.malloc(types, func, size))
+      end
+    end
+
+    def initialize_copy(other)
+      @entity = other.to_ptr.dup
+    end
+
     def each
       return enum_for(__function__) unless block_given?
 
@@ -75,6 +89,16 @@ class CUnion
     def CUnion.entity_class
       CUnionEntity
     end
+
+    def self.malloc(func=nil, &block)
+      if block
+        entity_class.malloc(types, func, size) do |entity|
+          block.call(new(entity))
+        end
+      else
+        new(entity_class.malloc(types, func, size))
+      end
+    end
   end
 
   # Wrapper for arrays within a struct
@@ -183,15 +207,6 @@ def create(klass, types, members)
         size = entity_class.size(types)
         define_singleton_method(:alignment) { alignment }
         define_singleton_method(:size) { size }
-        define_singleton_method(:malloc) do |func=nil, &block|
-          if block
-            entity_class.malloc(types, func, size) do |entity|
-              block.call(new(entity))
-            end
-          else
-            new(entity_class.malloc(types, func, size))
-          end
-        end
       }
       return new_class
     end
@@ -274,6 +289,12 @@ def initialize(addr, types, func = nil)
       super(addr, @size, func)
     end
 
+    # Initialize the memory for a struct and copy members from +other+.
+    def initialize_copy(other)
+      # TODO
+      super
+    end
+
     # Set the names of the +members+ in this C struct
     def assign_names(members)
       @members = []
diff --git a/test/fiddle/test_cstruct.rb b/test/fiddle/test_cstruct.rb
new file mode 100644
index 00000000..d71cc495
--- /dev/null
+++ b/test/fiddle/test_cstruct.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+begin
+  require_relative 'helper'
+rescue LoadError
+end
+
+module Fiddle
+  class TestStruct < TestCase
+    # https://github.com/ruby/fiddle/issues/66
+    def test_clone_gh_66
+      s = Fiddle::Importer.struct(["int i"])
+      a = s.malloc
+      a.i = 10
+      b = a.clone
+      b.i = 20
+      assert_equal({a: 10,  b: 20},
+                   {a: a.i, b: b.i})
+    end
+  end
+end