diff --git a/src/Extension/EscaperExtension.php b/src/Extension/EscaperExtension.php
index c5625fa6a41..6d9d1ce24d3 100644
--- a/src/Extension/EscaperExtension.php
+++ b/src/Extension/EscaperExtension.php
@@ -76,7 +76,7 @@ public function setEnvironment(Environment $environment): void
         }
 
         $this->environment = $environment;
-        $this->escaper = $environment->getRuntime(EscaperRuntime::class);
+        $this->escaper = null;
     }
 
     /**
@@ -140,16 +140,14 @@ public function setEscaper($strategy, callable $callable)
     {
         trigger_deprecation('twig/twig', '3.10', 'The "%s()" method is deprecated, use the "Twig\Runtime\EscaperRuntime::setEscaper()" method instead (be warned that Environment is not passed anymore to the callable).', __METHOD__);
 
-        if (!isset($this->environment)) {
-            throw new \LogicException(\sprintf('You must call "setEnvironment()" before calling "%s()".', __METHOD__));
-        }
+        $escaper = $this->getEscaper(__METHOD__);
 
         $this->escapers[$strategy] = $callable;
         $callable = function ($string, $charset) use ($callable) {
             return $callable($this->environment, $string, $charset);
         };
 
-        $this->escaper->setEscaper($strategy, $callable);
+        $escaper->setEscaper($strategy, $callable);
     }
 
     /**
@@ -175,11 +173,7 @@ public function setSafeClasses(array $safeClasses = [])
     {
         trigger_deprecation('twig/twig', '3.10', 'The "%s()" method is deprecated, use the "Twig\Runtime\EscaperRuntime::setSafeClasses()" method instead.', __METHOD__);
 
-        if (!isset($this->escaper)) {
-            throw new \LogicException(\sprintf('You must call "setEnvironment()" before calling "%s()".', __METHOD__));
-        }
-
-        $this->escaper->setSafeClasses($safeClasses);
+        $this->getEscaper(__METHOD__)->setSafeClasses($safeClasses);
     }
 
     /**
@@ -191,11 +185,20 @@ public function addSafeClass(string $class, array $strategies)
     {
         trigger_deprecation('twig/twig', '3.10', 'The "%s()" method is deprecated, use the "Twig\Runtime\EscaperRuntime::addSafeClass()" method instead.', __METHOD__);
 
-        if (!isset($this->escaper)) {
-            throw new \LogicException(\sprintf('You must call "setEnvironment()" before calling "%s()".', __METHOD__));
+        $this->getEscaper(__METHOD__)->addSafeClass($class, $strategies);
+    }
+
+    private function getEscaper(string $fromMethod): EscaperRuntime
+    {
+        if (isset($this->escaper)) {
+            return $this->escaper;
+        }
+
+        if (isset($this->environment)) {
+            return $this->escaper = $this->environment->getRuntime(EscaperRuntime::class);
         }
 
-        $this->escaper->addSafeClass($class, $strategies);
+        throw new \LogicException(\sprintf('You must call "setEnvironment()" before calling "%s()".', $fromMethod));
     }
 
     /**
diff --git a/tests/Extension/EscaperTest.php b/tests/Extension/EscaperTest.php
index 52f06950c9f..09aa4ca7935 100644
--- a/tests/Extension/EscaperTest.php
+++ b/tests/Extension/EscaperTest.php
@@ -25,6 +25,7 @@
 use Twig\Extension\EscaperExtension;
 use Twig\Loader\ArrayLoader;
 use Twig\Runtime\EscaperRuntime;
+use Twig\RuntimeLoader\FactoryRuntimeLoader;
 
 class EscaperTest extends TestCase
 {
@@ -80,6 +81,24 @@ public function testCustomEscapersOnMultipleEnvs()
         $this->assertSame('foo**ISO-8859-1**UTF-8**again', $env2->getRuntime(EscaperRuntime::class)->escape('foo', 'foo', 'ISO-8859-1'));
     }
 
+    /**
+     * @group legacy
+     */
+    public function testSafeClassesUseCustomRuntimeLoader()
+    {
+        $runtime = new EscaperRuntime();
+        $twig = new Environment(new ArrayLoader());
+        $twig->addRuntimeLoader(new FactoryRuntimeLoader([
+            EscaperRuntime::class => static fn () => $runtime,
+        ]));
+
+        $escaperExt = $twig->getExtension(EscaperExtension::class);
+        $escaperExt->addSafeClass('ThisClassIsSafe', ['html']);
+
+        $this->assertSame($runtime, $twig->getRuntime(EscaperRuntime::class));
+        $this->assertArrayHasKey('ThisClassIsSafe', $runtime->safeClasses);
+    }
+
     public function testLastModified()
     {
         $this->assertGreaterThan(1000000000, (new EscaperExtension())->getLastModified());