diff --git a/dist/index.js b/dist/index.js
index 28da2059..a05fdf63 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -1097,7 +1097,7 @@ var Options = function Options(obfuscatorOptions) {
         rotateUnicodeArray: Joi.boolean(),
         selfDefending: Joi.boolean(),
         sourceMap: Joi.boolean(),
-        sourceMapMode: Joi.string().allow(['inline', 'separate']),
+        sourceMapMode: Joi.string().valid(['inline', 'separate']),
         unicodeArray: Joi.boolean(),
         unicodeArrayThreshold: Joi.number().min(0).max(1),
         wrapUnicodeArrayCalls: Joi.boolean()
diff --git a/package.json b/package.json
index 1582b6c3..b6c7029a 100644
--- a/package.json
+++ b/package.json
@@ -26,7 +26,7 @@
     "escodegen": "^1.8.0",
     "esprima": "^2.7.2",
     "estraverse": "^4.2.0",
-    "joi": "^9.0.0",
+    "joi": "^6.10.0",
     "mkdirp": "^0.5.1",
     "source-map-support": "^0.4.1"
   },
diff --git a/src/Options.ts b/src/Options.ts
index 7c3b1ef9..13781782 100644
--- a/src/Options.ts
+++ b/src/Options.ts
@@ -88,7 +88,7 @@ export class Options implements IOptions {
         rotateUnicodeArray: Joi.boolean(),
         selfDefending: Joi.boolean(),
         sourceMap: Joi.boolean(),
-        sourceMapMode: Joi.string().allow(['inline', 'separate']),
+        sourceMapMode: Joi.string().valid(['inline', 'separate']),
         unicodeArray: Joi.boolean(),
         unicodeArrayThreshold: Joi.number().min(0).max(1),
         wrapUnicodeArrayCalls: Joi.boolean()