diff --git a/src/__tests__/fieldConverter-test.js b/src/__tests__/fieldConverter-test.js
index b4a71b49..714b288f 100644
--- a/src/__tests__/fieldConverter-test.js
+++ b/src/__tests__/fieldConverter-test.js
@@ -3,6 +3,7 @@
 
 import { EnumTypeComposer, schemaComposer, ListComposer, SchemaComposer } from 'graphql-compose';
 import { UserModel } from '../__mocks__/userModel';
+import { mongoose } from '../__mocks__/mongooseCommon';
 import {
   deriveComplexType,
   getFieldsFromModel,
@@ -199,6 +200,21 @@ describe('fieldConverter', () => {
       expect(genderEnum.getFieldNames().length).toBe(fields.gender.enumValues.length);
       expect(genderEnum.getField('male').value).toBe(fields.gender.enumValues[0]);
     });
+
+    it('should work for Enums with keys preparation', () => {
+      const model = mongoose.model(
+        'EnumTest',
+        mongoose.Schema({
+          oc: {
+            type: String,
+            enum: ['ocpp1.6', 'ocpp2.0'],
+          },
+        })
+      );
+      const flds: any = getFieldsFromModel(model);
+      const ocEnum = enumToGraphQL(flds.oc, '', schemaComposer);
+      expect(ocEnum.getFieldNames()).toEqual(['ocpp1_6', 'ocpp2_0']);
+    });
   });
 
   describe('embeddedToGraphQL()', () => {
diff --git a/src/fieldsConverter.js b/src/fieldsConverter.js
index 29bceba7..3c09a7fe 100644
--- a/src/fieldsConverter.js
+++ b/src/fieldsConverter.js
@@ -345,8 +345,9 @@ export function enumToGraphQL(
     const desc = _getFieldDescription(field);
     if (desc) etc.setDescription(desc);
 
-    const fields = valueList.reduce((result, val) => {
-      result[val] = { value: val }; // eslint-disable-line no-param-reassign
+    const fields = valueList.reduce((result, value) => {
+      const key = value.replace(/[^_a-zA-Z0-9]/g, '_');
+      result[key] = { value }; // eslint-disable-line no-param-reassign
       return result;
     }, {});
     etc.setFields(fields);