diff --git a/library/Icinga/Web/JavaScript.php b/library/Icinga/Web/JavaScript.php
index 1865136c76..3bdc1fead9 100644
--- a/library/Icinga/Web/JavaScript.php
+++ b/library/Icinga/Web/JavaScript.php
@@ -243,14 +243,26 @@ public static function optimizeDefine($js, $filePath, $basePath, $packageName)
                     continue;
                 }
 
-                if (preg_match('~^((?:\.\.?/)+)*(.*)~', $dependencyName, $natch)) {
+                $fileExtension = '.js';
+                $dirname = dirname($filePath);
+                if (preg_match('~^((?:\.\.?/)+)*.*?(\.\w+)?$~', $dependencyName, $natch)) {
+                    if (! empty($natch[1])) {
+                        $dependencyName = substr($dependencyName, strlen($natch[1]));
+                        $dirname = realpath(join(DIRECTORY_SEPARATOR, [$dirname, $natch[1]]));
+                    }
+
+                    if (! empty($natch[2])) {
+                        $dependencyName = substr($dependencyName, 0, -strlen($natch[2]));
+                        $fileExtension = $natch[2];
+                    }
+                }
+
+                $dependencyPath = join(DIRECTORY_SEPARATOR, [$dirname, $dependencyName . $fileExtension]);
+                if (file_exists($dependencyPath)) {
                     $dependencyName = join(DIRECTORY_SEPARATOR, array_filter([
                         $packageName,
-                        ltrim(substr(
-                            realpath(join(DIRECTORY_SEPARATOR, [dirname($filePath), $natch[1]])),
-                            strlen(realpath($basePath))
-                        ), DIRECTORY_SEPARATOR),
-                        $natch[2]
+                        trim(substr($dirname, strlen(realpath($basePath))), DIRECTORY_SEPARATOR . ' '),
+                        $dependencyName
                     ]));
                 }
             }
diff --git a/test/config/JavaScriptTest/someOther.js b/test/config/JavaScriptTest/someOther.js
new file mode 100644
index 0000000000..6f0f80c71f
--- /dev/null
+++ b/test/config/JavaScriptTest/someOther.js
@@ -0,0 +1,4 @@
+/* No requirements */
+define(function () {
+
+});
diff --git a/test/config/JavaScriptTest/someThing.js b/test/config/JavaScriptTest/someThing.js
new file mode 100644
index 0000000000..09bbec4bf7
--- /dev/null
+++ b/test/config/JavaScriptTest/someThing.js
@@ -0,0 +1,4 @@
+/* Relative path, No extension */
+define(["someThing/Else"], function (Else) {
+
+});
diff --git a/test/config/JavaScriptTest/someThing/Else.js b/test/config/JavaScriptTest/someThing/Else.js
new file mode 100644
index 0000000000..91707d723a
--- /dev/null
+++ b/test/config/JavaScriptTest/someThing/Else.js
@@ -0,0 +1,4 @@
+/* Relative path outside the current directory, With extension */
+define(["../someOther.js"], function (someOther) {
+
+});
diff --git a/test/php/library/Icinga/Web/JavaScriptTest.php b/test/php/library/Icinga/Web/JavaScriptTest.php
new file mode 100644
index 0000000000..64e12804b0
--- /dev/null
+++ b/test/php/library/Icinga/Web/JavaScriptTest.php
@@ -0,0 +1,102 @@
+<?php
+
+namespace Tests\Icinga\Web;
+
+use Icinga\Application\Icinga;
+use Icinga\Test\BaseTestCase;
+use Icinga\Web\JavaScript;
+use SplFileObject;
+
+class JavaScriptTest extends BaseTestCase
+{
+    protected $fileRoot;
+
+    public function setUp(): void
+    {
+        parent::setUp();
+
+        $this->fileRoot = Icinga::app()->getBaseDir('test/config/JavaScriptTest');
+    }
+
+    public function testLocalDefineOptimizations()
+    {
+        $expected = <<<'JS'
+/* Relative path, No extension */
+define("JavaScriptTest/someThing", ["JavaScriptTest/someThing/Else"], function (Else) {
+
+});
+
+JS;
+        $someThing = $this->getFile('someThing.js');
+        $this->assertSame($expected, $this->optimizeFile($someThing));
+
+        $expected = <<<'JS'
+/* Relative path outside the current directory, With extension */
+define("JavaScriptTest/someThing/Else", ["JavaScriptTest/someOther"], function (someOther) {
+
+});
+
+JS;
+        $someThingElse = $this->getFile('someThing/Else.js');
+        $this->assertSame($expected, $this->optimizeFile($someThingElse));
+    }
+
+    public function testNoRequirementsOptimization()
+    {
+        $expected = <<<'JS'
+define("JavaScriptTest/noRequirements", [], function () {
+
+});
+
+JS;
+        $source = <<<'JS'
+define(function () {
+
+});
+
+JS;
+        $this->assertSame($expected, JavaScript::optimizeDefine(
+            $source,
+            'JavaScriptTest/noRequirements',
+            'JavaScriptTest',
+            'JavaScriptTest'
+        ));
+    }
+
+    public function testGlobalRequirementsOptimization()
+    {
+        $expected = <<<'JS'
+define("JavaScriptTest/globalRequirements", ["SomeOtherTest/Anything"], function (Anything) {
+
+});
+
+JS;
+        $source = <<<'JS'
+define(["SomeOtherTest/Anything"], function (Anything) {
+
+});
+
+JS;
+        $this->assertSame($expected, JavaScript::optimizeDefine(
+            $source,
+            'JavaScriptTest/globalRequirements',
+            'JavaScriptTest',
+            'JavaScriptTest'
+        ));
+    }
+
+    protected function optimizeFile(SplFileObject $file): string
+    {
+        return JavaScript::optimizeDefine(
+            $file->fread($file->getSize()),
+            $file->getRealPath(),
+            $this->fileRoot,
+            'JavaScriptTest'
+        );
+    }
+
+    protected function getFile(string $file): SplFileObject
+    {
+        return new SplFileObject(join(DIRECTORY_SEPARATOR, [$this->fileRoot, $file]));
+    }
+}