diff --git a/src/lib/api/UrlHandlerApi.js b/src/lib/api/UrlHandlerApi.js
index 355ce722..055ab124 100644
--- a/src/lib/api/UrlHandlerApi.js
+++ b/src/lib/api/UrlHandlerApi.js
@@ -28,6 +28,10 @@ const replaceHistory = query => {
 
 /** Default URL parser implementation */
 class UrlParser {
+  constructor() {
+    this.parse = this.parse.bind(this);
+  }
+
   _sanitizeParamValue = value => {
     let parsedValue = parseInt(value);
     if (_isNaN(parsedValue)) {
@@ -51,7 +55,7 @@ class UrlParser {
    * Parse the URL query string and return an object with all the params.
    * @param {string} queryString the query string to parse
    */
-  parse = (queryString = '') => {
+  parse(queryString = '') {
     const parsedParams = Qs.parse(queryString, { ignoreQueryPrefix: true });
     const params = {};
     Object.entries(parsedParams).forEach(entry => {
@@ -60,7 +64,7 @@ class UrlParser {
       params[key] = this._sanitizeParamValue(value);
     });
     return params;
-  };
+  }
 }
 
 /** Default implementation for a param validator class */
@@ -113,6 +117,10 @@ export class UrlHandlerApi {
     Object.keys(this.urlParamsMapping).forEach(stateKey => {
       this.fromUrlParamsMapping[this.urlParamsMapping[stateKey]] = stateKey;
     });
+
+    this.get = this.get.bind(this);
+    this.set = this.set.bind(this);
+    this.replace = this.replace.bind(this);
   }
 
   /**
@@ -226,34 +234,34 @@ export class UrlHandlerApi {
    * Return a new version of the given `query` state with updated values parsed from the URL query string.
    * @param {object} queryState the `query` state
    */
-  get = queryState => {
+  get(queryState) {
     const urlParamsObj = this.urlParser.parse(window.location.search);
     const urlStateObj = this._mapUrlParamsToQueryState(urlParamsObj);
     const newQueryState = this._mergeParamsIntoState(urlStateObj, queryState);
     const newUrlParams = this._mapQueryStateToUrlParams(newQueryState);
     replaceHistory(newUrlParams);
     return newQueryState;
-  };
+  }
 
   /**
    * Update the URL query string parameters from the given `query` state
    * @param {object} stateQuery the `query` state
    */
-  set = stateQuery => {
+  set(stateQuery) {
     if (this.keepHistory) {
       const newUrlParams = this._mapQueryStateToUrlParams(stateQuery);
       pushHistory(newUrlParams);
     } else {
       this.replace(stateQuery);
     }
-  };
+  }
 
   /**
    * Replace the URL query string parameters from the given `query` state
    * @param {object} stateQuery the `query` state
    */
-  replace = stateQuery => {
+  replace(stateQuery) {
     const newUrlParams = this._mapQueryStateToUrlParams(stateQuery);
     replaceHistory(newUrlParams);
-  };
+  }
 }
diff --git a/src/lib/api/contrib/elasticsearch/ESRequestSerializer.js b/src/lib/api/contrib/elasticsearch/ESRequestSerializer.js
index 0c9416a0..4457260b 100644
--- a/src/lib/api/contrib/elasticsearch/ESRequestSerializer.js
+++ b/src/lib/api/contrib/elasticsearch/ESRequestSerializer.js
@@ -9,11 +9,15 @@
 import _isEmpty from 'lodash/isEmpty';
 
 export class ESRequestSerializer {
+  constructor() {
+    this.serialize = this.serialize.bind(this);
+  }
+
   /**
    * Return a serialized version of the app state `query` for the API backend.
    * @param {object} stateQuery the `query` state to serialize
    */
-  serialize = stateQuery => {
+  serialize(stateQuery) {
     const { queryString, sortBy, sortOrder, page, size } = stateQuery;
 
     const bodyParams = {};
@@ -41,5 +45,5 @@ export class ESRequestSerializer {
     }
 
     return bodyParams;
-  };
+  }
 }
diff --git a/src/lib/api/contrib/elasticsearch/ESResponseSerializer.js b/src/lib/api/contrib/elasticsearch/ESResponseSerializer.js
index dcafca38..17f6865b 100644
--- a/src/lib/api/contrib/elasticsearch/ESResponseSerializer.js
+++ b/src/lib/api/contrib/elasticsearch/ESResponseSerializer.js
@@ -7,15 +7,19 @@
  */
 
 export class ESResponseSerializer {
+  constructor() {
+    this.serialize = this.serialize.bind(this);
+  }
+
   /**
    * Return a serialized version of the API backend response for the app state `results`.
    * @param {object} payload the backend response payload
    */
-  serialize = payload => {
+  serialize(payload) {
     return {
       aggregations: payload.aggregations || {},
       hits: payload.hits.hits.map(hit => hit._source),
       total: payload.hits.total.value,
     };
-  };
+  }
 }
diff --git a/src/lib/api/contrib/elasticsearch/ESSearchApi.js b/src/lib/api/contrib/elasticsearch/ESSearchApi.js
index 6b35eee8..f9417065 100644
--- a/src/lib/api/contrib/elasticsearch/ESSearchApi.js
+++ b/src/lib/api/contrib/elasticsearch/ESSearchApi.js
@@ -19,6 +19,7 @@ export class ESSearchApi {
     this.initSerializers(config);
     this.initInterceptors(config);
     this.initAxios();
+    this.search = this.search.bind(this);
   }
 
   validateAxiosConfig() {
@@ -72,12 +73,12 @@ export class ESSearchApi {
    * Perform the backend request to search and return the serialized list of results for the app state `results`.
    * @param {string} stateQuery the `query` state with the user input
    */
-  search = async stateQuery => {
+  async search(stateQuery) {
     const payload = this.requestSerializer.serialize(stateQuery);
     const response = await this.http.request({
       method: 'POST',
       data: payload,
     });
     return this.responseSerializer.serialize(response.data);
-  };
+  }
 }
diff --git a/src/lib/api/contrib/invenio/InvenioRequestSerializer.js b/src/lib/api/contrib/invenio/InvenioRequestSerializer.js
index 741eefeb..669e173f 100644
--- a/src/lib/api/contrib/invenio/InvenioRequestSerializer.js
+++ b/src/lib/api/contrib/invenio/InvenioRequestSerializer.js
@@ -11,6 +11,10 @@ import _extend from 'lodash/extend';
 
 /** Default backend request serializer */
 export class InvenioRequestSerializer {
+  constructor() {
+    this.serialize = this.serialize.bind(this);
+  }
+
   _addFilter = (filter, filterUrlParams) => {
     if (!Array.isArray(filter)) {
       throw new Error(
@@ -58,7 +62,7 @@ export class InvenioRequestSerializer {
    * Return a serialized version of the app state `query` for the API backend.
    * @param {object} stateQuery the `query` state to serialize
    */
-  serialize = stateQuery => {
+  serialize(stateQuery) {
     const { queryString, sortBy, sortOrder, page, size, filters } = stateQuery;
 
     const getParams = {};
@@ -82,5 +86,5 @@ export class InvenioRequestSerializer {
     _extend(getParams, filterParams);
 
     return Qs.stringify(getParams, { arrayFormat: 'repeat' });
-  };
+  }
 }
diff --git a/src/lib/api/contrib/invenio/InvenioResponseSerializer.js b/src/lib/api/contrib/invenio/InvenioResponseSerializer.js
index 89964997..a6404e03 100644
--- a/src/lib/api/contrib/invenio/InvenioResponseSerializer.js
+++ b/src/lib/api/contrib/invenio/InvenioResponseSerializer.js
@@ -8,15 +8,19 @@
 
 /** Default backend response serializer */
 export class InvenioResponseSerializer {
+  constructor() {
+    this.serialize = this.serialize.bind(this);
+  }
+
   /**
    * Return a serialized version of the API backend response for the app state `results`.
    * @param {object} payload the backend response payload
    */
-  serialize = payload => {
+  serialize(payload) {
     return {
       aggregations: payload.aggregations || {},
       hits: payload.hits.hits,
       total: payload.hits.total,
     };
-  };
+  }
 }
diff --git a/src/lib/api/contrib/invenio/InvenioSearchApi.js b/src/lib/api/contrib/invenio/InvenioSearchApi.js
index 6d9a51d5..8231c883 100644
--- a/src/lib/api/contrib/invenio/InvenioSearchApi.js
+++ b/src/lib/api/contrib/invenio/InvenioSearchApi.js
@@ -19,6 +19,7 @@ export class InvenioSearchApi {
     this.initSerializers(config);
     this.initInterceptors(config);
     this.initAxios();
+    this.search = this.search.bind(this);
   }
 
   validateAxiosConfig() {
@@ -76,10 +77,10 @@ export class InvenioSearchApi {
    * Perform the backend request to search and return the serialized list of results for the app state `results`.
    * @param {string} stateQuery the `query` state with the user input
    */
-  search = async stateQuery => {
+  async search(stateQuery) {
     const response = await this.http.request({
       params: stateQuery,
     });
     return this.responseSerializer.serialize(response.data);
-  };
+  }
 }
diff --git a/src/lib/api/contrib/invenio/InvenioSuggestionApi.js b/src/lib/api/contrib/invenio/InvenioSuggestionApi.js
index a48d448e..ff54c020 100644
--- a/src/lib/api/contrib/invenio/InvenioSuggestionApi.js
+++ b/src/lib/api/contrib/invenio/InvenioSuggestionApi.js
@@ -14,13 +14,14 @@ import { InvenioSearchApi } from './InvenioSearchApi';
 class InvenioSuggestionRequestSerializer {
   constructor(queryField) {
     this.queryField = queryField;
+    this.serialize = this.serialize.bind(this);
   }
 
   /**
    * Return a serialized version of the app state `query` for the API backend.
    * @param {object} stateQuery the `query` state to serialize
    */
-  serialize = stateQuery => {
+  serialize(stateQuery) {
     const { suggestionString } = stateQuery;
 
     const getParams = {};
@@ -29,12 +30,13 @@ class InvenioSuggestionRequestSerializer {
     }
 
     return Qs.stringify(getParams, { arrayFormat: 'repeat', encode: false });
-  };
+  }
 }
 
 class InvenioSuggestionResponseSerializer {
   constructor(responseField) {
     this.responseFieldPath = responseField.split('.');
+    this.serialize = this.serialize.bind(this);
   }
 
   _serializeSuggestions = responseHits => {
@@ -49,11 +51,11 @@ class InvenioSuggestionResponseSerializer {
    * Return a serialized version of the API backend response for the app state `suggestions`.
    * @param {object} payload the backend response payload
    */
-  serialize = payload => {
+  serialize(payload) {
     return {
       suggestions: this._serializeSuggestions(payload.hits.hits || []),
     };
-  };
+  }
 }
 
 export class InvenioSuggestionApi extends InvenioSearchApi {
diff --git a/src/lib/components/ReactSearchKit/ReactSearchKit.test.js b/src/lib/components/ReactSearchKit/ReactSearchKit.test.js
index 4947086b..9cef4cb6 100644
--- a/src/lib/components/ReactSearchKit/ReactSearchKit.test.js
+++ b/src/lib/components/ReactSearchKit/ReactSearchKit.test.js
@@ -40,11 +40,10 @@ describe('test ReactSearchKit component', () => {
   it('should use default configuration', () => {
     const rsk = shallow(<ReactSearchKit searchApi={searchApi} />);
 
-    const mockUrlHandlerApi = new UrlHandlerApi();
     expect(configureStore).toBeCalledWith(
       expect.objectContaining({
         searchApi: searchApi,
-        urlHandlerApi: mockUrlHandlerApi,
+        urlHandlerApi: UrlHandlerApi.mock.instances[0],
       })
     );
     expect(UrlHandlerApi.mock.calls[0]).toMatchObject({});
@@ -94,11 +93,10 @@ describe('test ReactSearchKit component', () => {
       />
     );
 
-    const mockUrlHandlerApi = new UrlHandlerApi();
     expect(configureStore).toBeCalledWith(
       expect.objectContaining({
         searchApi: searchApi,
-        urlHandlerApi: mockUrlHandlerApi,
+        urlHandlerApi: UrlHandlerApi.mock.instances[0],
       })
     );
     expect(UrlHandlerApi.mock.calls[0][0]).toMatchObject({