diff --git a/src/RequirementChecker/RequirementsBuilder.php b/src/RequirementChecker/RequirementsBuilder.php
index 1cf8a9339..d8a5b4a2d 100644
--- a/src/RequirementChecker/RequirementsBuilder.php
+++ b/src/RequirementChecker/RequirementsBuilder.php
@@ -138,7 +138,7 @@ static function (array $sources): array {
                 usort(
                     $sources,
                     static fn (array $sourceTypePairA, array $sourceTypePairB) => strcmp(
-                        (string) $sourceTypePairA[0],
+                        $sourceTypePairA[0],
                         (string) $sourceTypePairB[0],
                     ),
                 );
diff --git a/tests/RequirementChecker/RequirementsBuilderTest.php b/tests/RequirementChecker/RequirementsBuilderTest.php
index 7331cea88..f98cad507 100644
--- a/tests/RequirementChecker/RequirementsBuilderTest.php
+++ b/tests/RequirementChecker/RequirementsBuilderTest.php
@@ -68,6 +68,10 @@ public function test_it_can_build_requirements_from_required_extensions(): void
             new Extension('http'),
             'package2',
         );
+        $this->builder->addRequiredExtension(
+            new Extension('http'),
+            null,
+        );
         $this->builder->addRequiredExtension(
             new Extension('phar'),
             'package1',
@@ -83,6 +87,7 @@ public function test_it_can_build_requirements_from_required_extensions(): void
         );
 
         $expected = new Requirements([
+            Requirement::forRequiredExtension('http', null),
             Requirement::forRequiredExtension('http', 'package1'),
             Requirement::forRequiredExtension('http', 'package2'),
             Requirement::forRequiredExtension('openssl', 'package3'),