diff --git a/bitser.lua b/bitser.lua
index 6a1c5b5..e04c17e 100644
--- a/bitser.lua
+++ b/bitser.lua
@@ -242,7 +242,7 @@ serialize_value = function(value, seen)
 		return
 	end
 	local t = type(value)
-	if t ~= 'number' and t ~= 'boolean' and t ~= 'nil' then
+	if t ~= 'number' and t ~= 'boolean' and t ~= 'nil' and t ~= 'cdata' then
 		seen[value] = seen[SEEN_LEN]
 		seen[SEEN_LEN] = seen[SEEN_LEN] + 1
 	end
diff --git a/cases/cdata.lua b/cases/cdata.lua
index 39f96f1..3227bed 100644
--- a/cases/cdata.lua
+++ b/cases/cdata.lua
@@ -12,12 +12,9 @@ struct nested_struct {
 };
 ]]
 
-local bitser = require 'bitser'
-
 local int_data = ffi.new('int', 5)
 
 local struct_data = ffi.new('struct nested_struct', {10, {20, 30}})
 
-local value = ffi.new('struct { int a; double b; }', 42, 1.25)
 
-return {int_data, struct_data, value}, 1000, 3
\ No newline at end of file
+return {int_data, struct_data, {ffi.new("int",1),5,ffi.new("int",67)}}, 1000, 3
\ No newline at end of file
diff --git a/spec/bitser_spec.lua b/spec/bitser_spec.lua
index e07861a..2692df8 100644
--- a/spec/bitser_spec.lua
+++ b/spec/bitser_spec.lua
@@ -332,4 +332,7 @@ describe("bitser", function()
 		local v = bitser.dumps(ffi.new('struct { int a; }'))
 		assert.has_error(function() bitser.loads(v) end)
 	end)
+	it("can read and write simple multiple cdata of the same ctype without getting confused", function()
+		test_serdeser({ffi.new('double', 42.5), ffi.new('double', 12), ffi.new('double', 0.01)})
+	end)
 end)