diff --git a/src/Type/FiniteTypeSet.php b/src/Type/FiniteTypeSet.php
index 4ed2714ef95..fc7c9de02f0 100644
--- a/src/Type/FiniteTypeSet.php
+++ b/src/Type/FiniteTypeSet.php
@@ -42,8 +42,6 @@ final class FiniteTypeSet
 
 	private const ENUM_CASE_KEY_PREFIX = 'enum:';
 
-	private ?bool $hasClassStringMember = null;
-
 	/**
 	 * @param array<string, Type> $members
 	 * @param array<string, Type> $membersByKind
@@ -256,36 +254,4 @@ public function containedInKey(string $key): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
-	/**
-	 * Whether a constant string member might also be a class-string.
-	 *
-	 * The class-string flag is part of a constant string's representation but not of its
-	 * value, so operations that pick a member to hand back - as opposed to merely comparing
-	 * values - cannot treat two same-valued constant strings as interchangeable. Answering
-	 * this costs a reflection lookup per string member, so it is computed on demand: only
-	 * combining operations ask.
-	 *
-	 * Every member is asked, no matter its kind: a keyed member is an instance of one of the
-	 * five classes key() accepts, and every one of them but ConstantStringType answers
-	 * isClassString() no outright - which is also the only one whose answer costs anything.
-	 */
-	public function hasClassStringMember(): bool
-	{
-		if ($this->hasClassStringMember !== null) {
-			return $this->hasClassStringMember;
-		}
-
-		$this->hasClassStringMember = false;
-		foreach ($this->members as $member) {
-			if ($member->isClassString()->no()) {
-				continue;
-			}
-
-			$this->hasClassStringMember = true;
-			break;
-		}
-
-		return $this->hasClassStringMember;
-	}
-
 }
diff --git a/src/Type/TypeCombinator.php b/src/Type/TypeCombinator.php
index 736c9aec7e6..dd298be650e 100644
--- a/src/Type/TypeCombinator.php
+++ b/src/Type/TypeCombinator.php
@@ -1595,10 +1595,6 @@ private static function finiteUnionMembers(UnionType $union): ?array
 			return null;
 		}
 
-		if ($finiteTypeSet->hasClassStringMember()) {
-			return null;
-		}
-
 		return $finiteTypeSet->getMembers();
 	}
 
diff --git a/tests/PHPStan/Type/FiniteTypeSetTest.php b/tests/PHPStan/Type/FiniteTypeSetTest.php
index c3fae75fe6a..3465b440baf 100644
--- a/tests/PHPStan/Type/FiniteTypeSetTest.php
+++ b/tests/PHPStan/Type/FiniteTypeSetTest.php
@@ -666,41 +666,6 @@ public function testUnionComparisonsRequireBothSetsToBeComplete(): void
 		$this->assertSame('Maybe', $union->isAcceptedBy($otherUnion, true)->result->describe());
 	}
 
-	/**
-	 * @return Iterator<string, array{list<Type>, bool}>
-	 */
-	public static function dataHasClassStringMember(): Iterator
-	{
-		yield 'plain strings' => [[new ConstantStringType('a'), new ConstantStringType('b')], false];
-		yield 'a value that names a class' => [[new ConstantStringType('a'), new ConstantStringType('DateTimeImmutable')], true];
-		yield 'the class-string flag' => [[new ConstantStringType('a'), new ConstantStringType('Zzz', true)], true];
-		// every member is asked, but only a string one can answer anything but no - not even
-		// an enum case, whose class name does name a class
-		yield 'no strings at all' => [
-			[
-				new ConstantIntegerType(1),
-				new ConstantBooleanType(true),
-				new NullType(),
-				new EnumCaseObjectType('PHPStan\Fixture\ManyCasesTestEnum', 'A'),
-			],
-			false,
-		];
-	}
-
-	/**
-	 * @param list<Type> $types
-	 */
-	#[DataProvider('dataHasClassStringMember')]
-	public function testHasClassStringMember(array $types, bool $expected): void
-	{
-		$set = FiniteTypeSet::create($types);
-		$this->assertNotNull($set);
-
-		$this->assertSame($expected, $set->hasClassStringMember());
-		// answered from the cache the second time round, with the same answer
-		$this->assertSame($expected, $set->hasClassStringMember());
-	}
-
 	public function testUnionWithoutFiniteMembersHasNoSet(): void
 	{
 		$this->assertNull((new UnionType([new StringType(), new IntegerType()]))->getFiniteTypeSet());