diff --git a/CHANGELOG.md b/CHANGELOG.md
index edb665ad8..0c4b66d1c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@ Change Log
 v5.4.1
 ---
 * Fixed missing space between keywords (`return`, `throw`, `typeof`) and Unicode surrogate pair identifiers in compact mode. Fixes https://github.com/javascript-obfuscator/javascript-obfuscator/issues/1112
+* Fixed `domainLock` being case-sensitive — domain values are now normalized to lowercase. Fixes https://github.com/javascript-obfuscator/javascript-obfuscator/issues/1182
 * Removed `source-map-support` runtime dependency. Use `node --enable-source-maps` instead. Fixes https://github.com/javascript-obfuscator/javascript-obfuscator/issues/1149
 
 v5.4.0
diff --git a/src/options/normalizer-rules/DomainLockRule.ts b/src/options/normalizer-rules/DomainLockRule.ts
index 030f035f4..677b645ca 100644
--- a/src/options/normalizer-rules/DomainLockRule.ts
+++ b/src/options/normalizer-rules/DomainLockRule.ts
@@ -13,7 +13,7 @@ export const DomainLockRule: TOptionsNormalizerRule = (options: IOptions): IOpti
         const normalizedDomains: string[] = [];
 
         for (const domain of options.domainLock) {
-            normalizedDomains.push(Utils.extractDomainFrom(domain));
+            normalizedDomains.push(Utils.extractDomainFrom(domain).toLowerCase());
         }
 
         options = {
diff --git a/test/functional-tests/issues/fixtures/issue1182.js b/test/functional-tests/issues/fixtures/issue1182.js
new file mode 100644
index 000000000..8e2f88daa
--- /dev/null
+++ b/test/functional-tests/issues/fixtures/issue1182.js
@@ -0,0 +1 @@
+var result = 42;
diff --git a/test/functional-tests/issues/issue1182.spec.ts b/test/functional-tests/issues/issue1182.spec.ts
new file mode 100644
index 000000000..428e8c9c2
--- /dev/null
+++ b/test/functional-tests/issues/issue1182.spec.ts
@@ -0,0 +1,43 @@
+import { assert } from 'chai';
+
+import { DomainLockRule } from '../../../src/options/normalizer-rules/DomainLockRule';
+import { IOptions } from '../../../src/interfaces/options/IOptions';
+
+//
+// https://github.com/javascript-obfuscator/javascript-obfuscator/issues/1182
+//
+describe('Issue #1182', () => {
+    describe('domainLock should be case-insensitive', () => {
+        it('should normalize mixed-case domain to lowercase', () => {
+            const options = DomainLockRule({
+                domainLock: ['Example.COM']
+            } as IOptions);
+
+            assert.deepEqual(options.domainLock, ['example.com']);
+        });
+
+        it('should normalize domain with subdomain to lowercase', () => {
+            const options = DomainLockRule({
+                domainLock: ['.Example.COM']
+            } as IOptions);
+
+            assert.deepEqual(options.domainLock, ['.example.com']);
+        });
+
+        it('should normalize multiple mixed-case domains', () => {
+            const options = DomainLockRule({
+                domainLock: ['Foo.Bar.COM', 'EXAMPLE.ORG']
+            } as IOptions);
+
+            assert.deepEqual(options.domainLock, ['foo.bar.com', 'example.org']);
+        });
+
+        it('should not change already-lowercase domains', () => {
+            const options = DomainLockRule({
+                domainLock: ['example.com']
+            } as IOptions);
+
+            assert.deepEqual(options.domainLock, ['example.com']);
+        });
+    });
+});