diff --git a/src/Testing/TypeInferenceTestCase.php b/src/Testing/TypeInferenceTestCase.php
index 2466b885bc..e24dbc7e3f 100644
--- a/src/Testing/TypeInferenceTestCase.php
+++ b/src/Testing/TypeInferenceTestCase.php
@@ -19,6 +19,7 @@
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\ConstantScalarType;
 use PHPStan\Type\FileTypeMapper;
+use PHPStan\Type\Type;
 use PHPStan\Type\VerbosityLevel;
 use function array_map;
 use function array_merge;
@@ -95,11 +96,18 @@ public function assertFileAsserts(
 	): void
 	{
 		if ($assertType === 'type') {
-			$expectedType = $args[0];
-			$this->assertInstanceOf(ConstantScalarType::class, $expectedType);
-			$expected = $expectedType->getValue();
-			$actualType = $args[1];
-			$actual = $actualType->describe(VerbosityLevel::precise());
+			if ($args[0] instanceof Type) {
+				// backward compatibility
+				$expectedType = $args[0];
+				$this->assertInstanceOf(ConstantScalarType::class, $expectedType);
+				$expected = $expectedType->getValue();
+				$actualType = $args[1];
+				$actual = $actualType->describe(VerbosityLevel::precise());
+			} else {
+				$expected = $args[0];
+				$actual = $args[1];
+			}
+
 			$this->assertSame(
 				$expected,
 				$actual,
@@ -142,12 +150,19 @@ public static function gatherAssertTypes(string $file): array
 				));
 			} elseif ($functionName === 'PHPStan\\Testing\\assertType') {
 				$expectedType = $scope->getType($node->getArgs()[0]->value);
+				if (!$expectedType instanceof ConstantScalarType) {
+					self::fail(sprintf('Expected type must be a literal string, %s given on line %d.', $expectedType->describe(VerbosityLevel::precise()), $node->getLine()));
+				}
 				$actualType = $scope->getType($node->getArgs()[1]->value);
-				$assert = ['type', $file, $expectedType, $actualType, $node->getLine()];
+				$assert = ['type', $file, $expectedType->getValue(), $actualType->describe(VerbosityLevel::precise()), $node->getLine()];
 			} elseif ($functionName === 'PHPStan\\Testing\\assertNativeType') {
 				$expectedType = $scope->getType($node->getArgs()[0]->value);
+				if (!$expectedType instanceof ConstantScalarType) {
+					self::fail(sprintf('Expected type must be a literal string, %s given on line %d.', $expectedType->describe(VerbosityLevel::precise()), $node->getLine()));
+				}
+
 				$actualType = $scope->getNativeType($node->getArgs()[1]->value);
-				$assert = ['type', $file, $expectedType, $actualType, $node->getLine()];
+				$assert = ['type', $file, $expectedType->getValue(), $actualType->describe(VerbosityLevel::precise()), $node->getLine()];
 			} elseif ($functionName === 'PHPStan\\Testing\\assertVariableCertainty') {
 				$certainty = $node->getArgs()[0]->value;
 				if (!$certainty instanceof StaticCall) {