diff --git a/src/Type/Php/SetTypeFunctionTypeSpecifyingExtension.php b/src/Type/Php/SetTypeFunctionTypeSpecifyingExtension.php
index 88c9dd86fc..c14d609440 100644
--- a/src/Type/Php/SetTypeFunctionTypeSpecifyingExtension.php
+++ b/src/Type/Php/SetTypeFunctionTypeSpecifyingExtension.php
@@ -10,10 +10,12 @@
 use PHPStan\Analyser\TypeSpecifierContext;
 use PHPStan\DependencyInjection\AutowiredService;
 use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\ErrorType;
 use PHPStan\Type\FunctionTypeSpecifyingExtension;
 use PHPStan\Type\NullType;
 use PHPStan\Type\ObjectType;
+use PHPStan\Type\ObjectWithoutClassType;
 use PHPStan\Type\TypeCombinator;
 use stdClass;
 use function count;
@@ -41,7 +43,15 @@ public function specifyTypes(FunctionReflection $functionReflection, FuncCall $n
 
 		$constantStrings = $castType->getConstantStrings();
 		if (count($constantStrings) < 1) {
-			return new SpecifiedTypes();
+			$constantStrings = [
+				new ConstantStringType('bool'),
+				new ConstantStringType('int'),
+				new ConstantStringType('float'),
+				new ConstantStringType('string'),
+				new ConstantStringType('array'),
+				new ConstantStringType('object'),
+				new ConstantStringType('null'),
+			];
 		}
 
 		$types = [];
@@ -67,7 +77,17 @@ public function specifyTypes(FunctionReflection $functionReflection, FuncCall $n
 					$types[] = $valueType->toArray();
 					break;
 				case 'object':
-					$types[] = new ObjectType(stdClass::class);
+					$isObject = $valueType->isObject();
+					if ($isObject->yes()) {
+						$types[] = $valueType;
+					} elseif ($isObject->no()) {
+						$types[] = new ObjectType(stdClass::class);
+					} else {
+						$types[] = TypeCombinator::union(
+							TypeCombinator::intersect($valueType, new ObjectWithoutClassType()),
+							new ObjectType(stdClass::class),
+						);
+					}
 					break;
 				case 'null':
 					$types[] = new NullType();
diff --git a/tests/PHPStan/Analyser/nsrt/bug-3250.php b/tests/PHPStan/Analyser/nsrt/bug-3250.php
new file mode 100644
index 0000000000..ec52c27fe9
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-3250.php
@@ -0,0 +1,61 @@
+<?php declare(strict_types = 1);
+
+namespace Bug3250;
+
+use DateTime;
+use stdClass;
+use function PHPStan\Testing\assertType;
+
+function castTo(string $value, string $castTo): void
+{
+	$newValue = $value;
+	settype($newValue, $castTo);
+
+	assertType('array{string}|bool|float|int|stdClass|string|null', $newValue);
+}
+
+function castToInt(string $value): void
+{
+	$newValue = $value;
+	settype($newValue, 'int');
+
+	assertType('int', $newValue);
+}
+
+/**
+ * @param 'int'|'float' $castTo
+ */
+function castToIntOrFloat(string $value, string $castTo): void
+{
+	$newValue = $value;
+	settype($newValue, $castTo);
+
+	assertType('float|int', $newValue);
+}
+
+function castObjectToObject(DateTime $value): void
+{
+	$newValue = $value;
+	settype($newValue, 'object');
+
+	assertType('DateTime', $newValue);
+}
+
+/**
+ * @param DateTime|string $value
+ */
+function castMixedToObject($value): void
+{
+	$newValue = $value;
+	settype($newValue, 'object');
+
+	assertType('DateTime|stdClass', $newValue);
+}
+
+function castStringToObject(string $value): void
+{
+	$newValue = $value;
+	settype($newValue, 'object');
+
+	assertType('stdClass', $newValue);
+}
diff --git a/tests/PHPStan/Analyser/nsrt/set-type-type-specifying.php b/tests/PHPStan/Analyser/nsrt/set-type-type-specifying.php
index f7513c6045..ef0f894c63 100644
--- a/tests/PHPStan/Analyser/nsrt/set-type-type-specifying.php
+++ b/tests/PHPStan/Analyser/nsrt/set-type-type-specifying.php
@@ -146,7 +146,7 @@ function doObject(string $s, int $i, float $f, array $a, object $o)
 	assertType('stdClass', $a);
 
 	settype($o, 'object');
-	assertType('stdClass', $o);
+	assertType('object', $o);
 }
 
 function doNull(string $s, int $i, float $f, array $a, object $o)
@@ -669,5 +669,5 @@ function setTypeSpecifying($value, string $castTo): void
 
 	// Mixed to non-constant.
 	settype($value, $castTo);
-	assertType("array|bool|float|int|stdClass|string|null", $value);
+	assertType("array|bool|float|int|object|string|null", $value);
 }