diff --git a/src/Rules/RuleErrorBuilder.php b/src/Rules/RuleErrorBuilder.php
index 443f8ec79..35c4d4c25 100644
--- a/src/Rules/RuleErrorBuilder.php
+++ b/src/Rules/RuleErrorBuilder.php
@@ -8,6 +8,7 @@
 use function class_exists;
 use function count;
 use function implode;
+use function is_file;
 use function sprintf;
 
 /**
@@ -143,6 +144,9 @@ public function line(int $line): self
 	 */
 	public function file(string $file, ?string $fileDescription = null): self
 	{
+		if (!is_file($file)) {
+			throw new ShouldNotHappenException(sprintf('File %s does not exist.', $file));
+		}
 		$this->properties['file'] = $file;
 		$this->properties['fileDescription'] = $fileDescription ?? $file;
 		$this->type |= self::TYPE_FILE;
diff --git a/tests/PHPStan/Rules/RuleErrorBuilderTest.php b/tests/PHPStan/Rules/RuleErrorBuilderTest.php
index bb59e928b..59826f717 100644
--- a/tests/PHPStan/Rules/RuleErrorBuilderTest.php
+++ b/tests/PHPStan/Rules/RuleErrorBuilderTest.php
@@ -26,24 +26,24 @@ public function testMessageAndLineAndBuild(): void
 
 	public function testMessageAndFileAndBuild(): void
 	{
-		$builder = RuleErrorBuilder::message('Foo')->file('Bar.php');
+		$builder = RuleErrorBuilder::message('Foo')->file(__FILE__);
 		$ruleError = $builder->build();
 		$this->assertSame('Foo', $ruleError->getMessage());
 
 		$this->assertInstanceOf(FileRuleError::class, $ruleError); // @phpstan-ignore method.alreadyNarrowedType
-		$this->assertSame('Bar.php', $ruleError->getFile());
+		$this->assertSame(__FILE__, $ruleError->getFile());
 	}
 
 	public function testMessageAndLineAndFileAndBuild(): void
 	{
-		$builder = RuleErrorBuilder::message('Foo')->line(25)->file('Bar.php');
+		$builder = RuleErrorBuilder::message('Foo')->line(25)->file(__FILE__);
 		$ruleError = $builder->build();
 		$this->assertSame('Foo', $ruleError->getMessage());
 
 		$this->assertInstanceOf(LineRuleError::class, $ruleError); // @phpstan-ignore method.alreadyNarrowedType
 		$this->assertInstanceOf(FileRuleError::class, $ruleError);  // @phpstan-ignore method.alreadyNarrowedType
 		$this->assertSame(25, $ruleError->getLine());
-		$this->assertSame('Bar.php', $ruleError->getFile());
+		$this->assertSame(__FILE__, $ruleError->getFile());
 	}
 
 }