diff --git a/tests/Support/SupportNumberTest.php b/tests/Support/SupportNumberTest.php
index eaa47d0adf6b..eba64b8b139a 100644
--- a/tests/Support/SupportNumberTest.php
+++ b/tests/Support/SupportNumberTest.php
@@ -87,16 +87,16 @@ public function testSpelloutWithLocale()
     #[RequiresPhpExtension('intl')]
     public function testSpelloutWithThreshold()
     {
-        $this->assertSame('9', Number::spell(9, after: 10));
-        $this->assertSame('10', Number::spell(10, after: 10));
-        $this->assertSame('eleven', Number::spell(11, after: 10));
+        $this->assertSame('9', (string) Number::spell(9, after: 10));
+        $this->assertSame('10', (string) Number::spell(10, after: 10));
+        $this->assertSame('eleven', (string) Number::spell(11, after: 10));
 
-        $this->assertSame('nine', Number::spell(9, until: 10));
-        $this->assertSame('10', Number::spell(10, until: 10));
-        $this->assertSame('11', Number::spell(11, until: 10));
+        $this->assertSame('nine', (string) Number::spell(9, until: 10));
+        $this->assertSame('10', (string) Number::spell(10, until: 10));
+        $this->assertSame('11', (string) Number::spell(11, until: 10));
 
-        $this->assertSame('ten thousand', Number::spell(10000, until: 50000));
-        $this->assertSame('100,000', Number::spell(100000, until: 50000));
+        $this->assertSame('ten thousand', (string) Number::spell(10000, until: 50000));
+        $this->assertSame('100,000', (string) Number::spell(100000, until: 50000));
     }
 
     public function testOrdinal()