diff --git a/pkg/api/serialization_test.go b/pkg/api/serialization_test.go
index 4f9fa87964f..27a2e352641 100644
--- a/pkg/api/serialization_test.go
+++ b/pkg/api/serialization_test.go
@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"encoding/hex"
 	"encoding/json"
+	"fmt"
 	"io/ioutil"
 	"math/rand"
 	"reflect"
@@ -78,6 +79,13 @@ func dataAsString(data []byte) string {
 func roundTrip(t *testing.T, codec runtime.Codec, item runtime.Object) {
 	printer := spew.ConfigState{DisableMethods: true}
 
+	original := item
+	copied, err := api.Scheme.DeepCopy(item)
+	if err != nil {
+		panic(fmt.Sprintf("unable to copy: %v", err))
+	}
+	item = copied.(runtime.Object)
+
 	name := reflect.TypeOf(item).Elem().Name()
 	data, err := runtime.Encode(codec, item)
 	if err != nil {
@@ -85,13 +93,18 @@ func roundTrip(t *testing.T, codec runtime.Codec, item runtime.Object) {
 		return
 	}
 
+	if !api.Semantic.DeepEqual(original, item) {
+		t.Errorf("0: %v: encode altered the object, diff: %v", name, diff.ObjectReflectDiff(original, item))
+		return
+	}
+
 	obj2, err := runtime.Decode(codec, data)
 	if err != nil {
-		t.Errorf("0: %v: %v\nCodec: %v\nData: %s\nSource: %#v", name, err, codec, dataAsString(data), printer.Sprintf("%#v", item))
+		t.Errorf("0: %v: %v\nCodec: %#v\nData: %s\nSource: %#v", name, err, codec, dataAsString(data), printer.Sprintf("%#v", item))
 		panic("failed")
 	}
-	if !api.Semantic.DeepEqual(item, obj2) {
-		t.Errorf("\n1: %v: diff: %v\nCodec: %v\nSource:\n\n%#v\n\nEncoded:\n\n%s\n\nFinal:\n\n%#v", name, diff.ObjectGoPrintDiff(item, obj2), codec, printer.Sprintf("%#v", item), dataAsString(data), printer.Sprintf("%#v", obj2))
+	if !api.Semantic.DeepEqual(original, obj2) {
+		t.Errorf("\n1: %v: diff: %v\nCodec: %#v\nSource:\n\n%#v\n\nEncoded:\n\n%s\n\nFinal:\n\n%#v", name, diff.ObjectReflectDiff(item, obj2), codec, printer.Sprintf("%#v", item), dataAsString(data), printer.Sprintf("%#v", obj2))
 		return
 	}
 
@@ -101,7 +114,7 @@ func roundTrip(t *testing.T, codec runtime.Codec, item runtime.Object) {
 		return
 	}
 	if !api.Semantic.DeepEqual(item, obj3) {
-		t.Errorf("3: %v: diff: %v\nCodec: %v", name, diff.ObjectDiff(item, obj3), codec)
+		t.Errorf("3: %v: diff: %v\nCodec: %#v", name, diff.ObjectReflectDiff(item, obj3), codec)
 		return
 	}
 }
diff --git a/pkg/api/v1/conversion_test.go b/pkg/api/v1/conversion_test.go
index ac0b4e682f0..205777cd28e 100644
--- a/pkg/api/v1/conversion_test.go
+++ b/pkg/api/v1/conversion_test.go
@@ -204,8 +204,8 @@ func TestResourceListConversion(t *testing.T) {
 		},
 	}
 
-	output := api.ResourceList{}
 	for i, test := range tests {
+		output := api.ResourceList{}
 		err := api.Scheme.Convert(&test.input, &output)
 		if err != nil {
 			t.Fatalf("unexpected error for case %d: %v", i, err)