diff --git a/packages/soql-builder-ui/.eslintrc.json b/packages/soql-builder-ui/.eslintrc.json
index 4006118f..963d114f 100644
--- a/packages/soql-builder-ui/.eslintrc.json
+++ b/packages/soql-builder-ui/.eslintrc.json
@@ -9,6 +9,7 @@
     "@lwc/lwc/no-async-operation": "off",
     "@lwc/lwc/no-inner-html": "warn",
     "@lwc/lwc/no-document-query": "warn",
-    "no-underscore-dangle": "off"
+    "no-underscore-dangle": "off",
+    "@typescript-eslint/no-unused-vars": "warn"
   }
 }
diff --git a/packages/soql-builder-ui/package.json b/packages/soql-builder-ui/package.json
index 970eec06..8084aa28 100644
--- a/packages/soql-builder-ui/package.json
+++ b/packages/soql-builder-ui/package.json
@@ -44,7 +44,7 @@
   "license": "BSD-3-Clause",
   "main": "dist/",
   "scripts": {
-    "build": "lwc-services build -w webpack.config.js -m production",
+    "build": "export NODE_OPTIONS=--openssl-legacy-provider && lwc-services build -w webpack.config.js -m production",
     "clean": "shx rm -rf package-lock.json && shx rm -rf dist && shx rm -rf node_modules",
     "publish:lwc": "npm publish .",
     "lint": "eslint ./src",
diff --git a/packages/soql-builder-ui/tsconfig.json b/packages/soql-builder-ui/tsconfig.json
index e69de29b..0967ef42 100644
--- a/packages/soql-builder-ui/tsconfig.json
+++ b/packages/soql-builder-ui/tsconfig.json
@@ -0,0 +1 @@
+{}
diff --git a/packages/soql-model/src/validators/stringValidator.test.ts b/packages/soql-model/src/validators/stringValidator.test.ts
index ef787fae..cfdcbdfd 100644
--- a/packages/soql-model/src/validators/stringValidator.test.ts
+++ b/packages/soql-model/src/validators/stringValidator.test.ts
@@ -16,9 +16,16 @@ describe('StringValidator should', () => {
   it('return valid result for string in single quotes', () => {
     expect(validator.validate("'foo'")).toEqual(validResult);
   });
+
+  it('return valid result when user input is NULL or null', () => {
+    expect(validator.validate("'null'")).toEqual(validResult);
+    expect(validator.validate("'NULL'")).toEqual(validResult);
+  });
+
   it('return not valid result for non-string value', () => {
     expect(validator.validate('foo')).toEqual(notValidResult);
   });
+
   it('return not valid result for string ending in escaped quote', () => {
     expect(validator.validate("'foo\\'")).toEqual(notValidResult);
   });
diff --git a/packages/soql-model/src/validators/stringValidator.ts b/packages/soql-model/src/validators/stringValidator.ts
index 966072ae..6d0f356c 100644
--- a/packages/soql-model/src/validators/stringValidator.ts
+++ b/packages/soql-model/src/validators/stringValidator.ts
@@ -10,10 +10,11 @@ import { ValidateResult, Validator } from './validator';
 export class StringValidator extends Validator {
   public validate(input: string): ValidateResult {
     const isValid =
-      input.length >= 2 &&
-      input.startsWith("'") &&
-      input.endsWith("'") &&
-      !this.isEscaped(input.substring(1, input.length - 1));
+      (input.length >= 2 &&
+        input.startsWith("'") &&
+        input.endsWith("'") &&
+        !this.isEscaped(input.substring(1, input.length - 1))) ||
+      input.toLowerCase() === 'null';
     const message = isValid ? undefined : Messages.error_fieldInput_string;
     return { isValid, message };
   }