diff --git a/lib/config/configuration.js b/lib/config/configuration.js
index 207327c..428ac0b 100644
--- a/lib/config/configuration.js
+++ b/lib/config/configuration.js
@@ -35,7 +35,8 @@ export class Configuration {
 
   static withConfiguration(aConfiguration) {
     const defaultConfiguration = require('./default_configuration.json');
-    return new this(aConfiguration, defaultConfiguration);
+    const userConfiguration = require(resolvePathFor(CONFIGURATION_FILE_NAME));
+    return new this({ ...userConfiguration, ...aConfiguration }, defaultConfiguration);
   }
   constructor(userConfiguration, defaultConfiguration) {
     this.#userConfigurationOptions = userConfiguration;
diff --git a/lib/config/parameters_parser.js b/lib/config/parameters_parser.js
index 15b7963..27c4dbf 100644
--- a/lib/config/parameters_parser.js
+++ b/lib/config/parameters_parser.js
@@ -1,10 +1,10 @@
+import { I18n } from '../i18n/i18n.js';
+import { isString } from '../utils.js';
+
 /**
  * I transform a list of console parameters into a valid configuration object.
  * I can also differentiate between path parameters and configuration parameters.
  */
-import { I18n } from '../i18n/i18n.js';
-import { isString } from '../utils.js';
-
 export class ParametersParser {
 
   static generateRunConfigurationFromParams(params) {
@@ -56,11 +56,11 @@ export class ParametersParser {
   }
 
   static getPathsAndConfigurationParams(allParams) {
-    const firstConfigParamIndex = allParams.findIndex(param => this.isConfigurationParam(param));
+    const firstConfigParamIndex = allParams.findIndex(param => this.isRawConfigurationParam(param));
 
     if (firstConfigParamIndex >= 0) {
       const paramsAfterFirstConfigurationParam = allParams.slice(firstConfigParamIndex);
-      const thereIsPathParamAfterConfigParams = paramsAfterFirstConfigurationParam.some(param => !this.isConfigurationParam(param));
+      const thereIsPathParamAfterConfigParams = paramsAfterFirstConfigurationParam.some(param => !this.isRawConfigurationParam(param));
       if (thereIsPathParamAfterConfigParams) {
         throw new Error('Run configuration parameters should always be sent at the end of test paths routes');
       }
@@ -80,6 +80,12 @@ export class ParametersParser {
     return this.isFailFastParam(param) || this.isRandomizeParam(param) || this.isLanguageParam(param);
   }
 
+  static isRawConfigurationParam(param) {
+    // pre sanitization
+    const supportedLanguages = I18n.supportedLanguages();
+    return this.isConfigurationParam(param) || supportedLanguages.includes(param);
+  }
+
   static isFailFastParam(string) {
     return isString(string) && (string === '-f' || string === '--fail-fast');
   }