diff --git a/packages/field/src/FormatMixin.js b/packages/field/src/FormatMixin.js
index 79b0b4758..b5c17cfef 100644
--- a/packages/field/src/FormatMixin.js
+++ b/packages/field/src/FormatMixin.js
@@ -164,7 +164,7 @@ export const FormatMixin = dedupeMixin(
        * @returns {String} serializedValue
        */
       serializer(v) {
-        return v;
+        return v !== undefined ? v : '';
       }
 
       /**
@@ -175,7 +175,7 @@ export const FormatMixin = dedupeMixin(
        * @returns {Object} modelValue
        */
       deserializer(v) {
-        return v;
+        return v === undefined ? '' : v;
       }
 
       /**