diff --git a/handler/api/card/create_test.go b/handler/api/card/create_test.go
index 77e814562..37760b7f7 100644
--- a/handler/api/card/create_test.go
+++ b/handler/api/card/create_test.go
@@ -45,7 +45,7 @@ var (
 	}
 	dummyCreateCard = &core.CreateCard{
 		Schema: "https://myschema.com",
-		Data:   "{\"type\": \"AdaptiveCard\"}",
+		Data:   []byte("{\"type\": \"AdaptiveCard\"}"),
 	}
 	dummyCard = &core.Card{
 		Id:     1,
diff --git a/mock/mock_gen.go b/mock/mock_gen.go
index 224d6474f..e26fd1be4 100644
--- a/mock/mock_gen.go
+++ b/mock/mock_gen.go
@@ -2962,10 +2962,10 @@ func (mr *MockCardStoreMockRecorder) FindCardByBuild(arg0, arg1 interface{}) *go
 }
 
 // FindCardData mocks base method.
-func (m *MockCardStore) FindCardData(arg0 context.Context, arg1 int64) (io.Reader, error) {
+func (m *MockCardStore) FindCardData(arg0 context.Context, arg1 int64) (io.ReadCloser, error) {
 	m.ctrl.T.Helper()
 	ret := m.ctrl.Call(m, "FindCardData", arg0, arg1)
-	ret0, _ := ret[0].(io.Reader)
+	ret0, _ := ret[0].(io.ReadCloser)
 	ret1, _ := ret[1].(error)
 	return ret0, ret1
 }
diff --git a/store/card/card_test.go b/store/card/card_test.go
index 8aa22e5d9..5bb962cdd 100644
--- a/store/card/card_test.go
+++ b/store/card/card_test.go
@@ -52,7 +52,7 @@ func testCardCreate(store *cardStore) func(t *testing.T) {
 			Stage:  2,
 			Step:   3,
 			Schema: "https://myschema.com",
-			Data:   "{\"type\": \"AdaptiveCard\"}",
+			Data:   []byte("{\"type\": \"AdaptiveCard\"}"),
 		}
 		err := store.CreateCard(noContext, item)
 		if err != nil {