diff --git a/system/HTTP/SiteURI.php b/system/HTTP/SiteURI.php
index 372d3939eb15..c9c8cc566519 100644
--- a/system/HTTP/SiteURI.php
+++ b/system/HTTP/SiteURI.php
@@ -73,10 +73,12 @@ class SiteURI extends URI
     /**
      * @param string $relativePath URI path relative to baseURL. May include
      *                             queries or fragments.
-     * @param string $host         Hostname. If it is not in $allowedHostnames,
+     * @param string $host         Optional hostname. If it is not in $allowedHostnames,
      *                             just be ignored.
+     * @param string $scheme       Optional scheme. 'http' or 'https'.
+     * @phpstan-param 'http'|'https'|'' $scheme
      */
-    public function __construct(App $configApp, string $relativePath = '', string $host = '')
+    public function __construct(App $configApp, string $relativePath = '', string $host = '', string $scheme = '')
     {
         $this->baseURL   = $this->normalizeBaseURL($configApp);
         $this->indexPage = $configApp->indexPage;
@@ -100,7 +102,9 @@ public function __construct(App $configApp, string $relativePath = '', string $h
         $uri     = new URI($tempUri);
 
         // Update scheme
-        if ($configApp->forceGlobalSecureRequests) {
+        if ($scheme !== '') {
+            $uri->setScheme($scheme);
+        } elseif ($configApp->forceGlobalSecureRequests) {
             $uri->setScheme('https');
         }
 
diff --git a/tests/system/HTTP/SiteURITest.php b/tests/system/HTTP/SiteURITest.php
index 413ab66ee57c..bdc6679bacc1 100644
--- a/tests/system/HTTP/SiteURITest.php
+++ b/tests/system/HTTP/SiteURITest.php
@@ -70,6 +70,16 @@ public function testConstructorHost()
         $this->assertSame('/index.php/', $uri->getPath());
     }
 
+    public function testConstructorScheme()
+    {
+        $config = new App();
+
+        $uri = new SiteURI($config, '', '', 'https');
+
+        $this->assertInstanceOf(SiteURI::class, $uri);
+        $this->assertSame('https://example.com/index.php/', (string) $uri);
+    }
+
     public function testConstructorSubfolder()
     {
         $config          = new App();