diff --git a/src/Rules/Keywords/RequireFileExistsRule.php b/src/Rules/Keywords/RequireFileExistsRule.php
index b0d4def309..0a3e6e35a5 100644
--- a/src/Rules/Keywords/RequireFileExistsRule.php
+++ b/src/Rules/Keywords/RequireFileExistsRule.php
@@ -3,15 +3,21 @@
 namespace PHPStan\Rules\Keywords;
 
 use PhpParser\Node;
+use PhpParser\Node\Arg;
+use PhpParser\Node\Expr;
+use PhpParser\Node\Expr\FuncCall;
 use PhpParser\Node\Expr\Include_;
+use PhpParser\Node\Name\FullyQualified;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\AutowiredParameter;
 use PHPStan\DependencyInjection\RegisteredRule;
 use PHPStan\File\FileHelper;
+use PHPStan\Node\Printer\ExprPrinter;
 use PHPStan\Rules\IdentifierRuleError;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\ShouldNotHappenException;
+use PHPStan\Type\Constant\ConstantStringType;
 use function array_merge;
 use function dirname;
 use function explode;
@@ -30,6 +36,7 @@ final class RequireFileExistsRule implements Rule
 	public function __construct(
 		#[AutowiredParameter]
 		private string $currentWorkingDirectory,
+		private ExprPrinter $exprPrinter,
 	)
 	{
 	}
@@ -41,15 +48,28 @@ public function getNodeType(): string
 
 	public function processNode(Node $node, Scope $scope): array
 	{
+		if ($this->isInFileExists($node, $scope)) {
+			return [];
+		}
+
 		$errors = [];
-		$paths = $this->resolveFilePaths($node, $scope);
+		$usedMagicDirFallback = false;
+		$paths = $this->resolveFilePaths($node, $scope, $usedMagicDirFallback);
 
 		foreach ($paths as $path) {
+			$path = $path->getValue();
+
 			if ($this->doesFileExist($path, $scope)) {
 				continue;
 			}
 
-			$errors[] = $this->getErrorMessage($node, $path);
+			if ($usedMagicDirFallback) {
+				$pathExpr = $this->exprPrinter->printExpr($node->expr);
+			} else {
+				$pathExpr = '"' . $path . '"';
+			}
+
+			$errors[] = $this->getErrorMessage($node, $pathExpr);
 		}
 
 		return $errors;
@@ -90,7 +110,7 @@ private function doesFileExistForDirectory(string $path, string $workingDirector
 
 	private function getErrorMessage(Include_ $node, string $filePath): IdentifierRuleError
 	{
-		$message = 'Path in %s() "%s" is not a file or it does not exist.';
+		$message = 'Path in %s() %s is not a file or it does not exist.';
 
 		switch ($node->type) {
 			case Include_::TYPE_REQUIRE:
@@ -125,19 +145,43 @@ private function getErrorMessage(Include_ $node, string $filePath): IdentifierRu
 	}
 
 	/**
-	 * @return array<string>
+	 * @return list<ConstantStringType>
 	 */
-	private function resolveFilePaths(Include_ $node, Scope $scope): array
+	private function resolveFilePaths(Include_ $node, Scope $scope, bool &$magicDirFallback): array
+	{
+		$magicDirFallback = false;
+		$expr = $node->expr;
+
+		if (!$expr instanceof Expr\BinaryOp\Concat) {
+			return $scope->getType($expr)->getConstantStrings();
+		}
+
+		if ($expr->left instanceof Node\Scalar\MagicConst\Dir) {
+			$magicDirFallback = true;
+
+			$paths = [];
+			foreach ($scope->getType($expr->right)->getConstantStrings() as $constantString) {
+				$paths[] = new ConstantStringType(dirname($scope->getFile()) . $constantString->getValue());
+			}
+			return $paths;
+		}
+
+		return $scope->getType($expr)->getConstantStrings();
+	}
+
+	private function isInFileExists(Include_ $node, Scope $scope): bool
 	{
-		$paths = [];
-		$type = $scope->getType($node->expr);
-		$constantStrings = $type->getConstantStrings();
+		foreach (['file_exists', 'is_file'] as $funcName) {
+			$expr = new FuncCall(new FullyQualified($funcName), [
+				new Arg($node->expr),
+			]);
 
-		foreach ($constantStrings as $constantString) {
-			$paths[] = $constantString->getValue();
+			if ($scope->getType($expr)->isTrue()->yes()) {
+				return true;
+			}
 		}
 
-		return $paths;
+		return false;
 	}
 
 }
diff --git a/tests/PHPStan/Rules/Keywords/RequireFileExistsRuleNoConstantPathTest.php b/tests/PHPStan/Rules/Keywords/RequireFileExistsRuleNoConstantPathTest.php
new file mode 100644
index 0000000000..b967cdbe56
--- /dev/null
+++ b/tests/PHPStan/Rules/Keywords/RequireFileExistsRuleNoConstantPathTest.php
@@ -0,0 +1,44 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Keywords;
+
+use PHPStan\Node\Printer\ExprPrinter;
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/**
+ * @extends RuleTestCase<RequireFileExistsRule>
+ */
+class RequireFileExistsRuleNoConstantPathTest extends RuleTestCase
+{
+
+	private string $currentWorkingDirectory = __DIR__ . '/../';
+
+	protected function getRule(): Rule
+	{
+		return new RequireFileExistsRule(
+			$this->currentWorkingDirectory,
+			self::getContainer()->getByType(ExprPrinter::class),
+		);
+	}
+
+	public function testBug12203NoConstantPath(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-12203.php'], [
+			[
+				'Path in require_once() "../bug-12203-sure-does-not-exist.php" is not a file or it does not exist.',
+				5,
+			],
+			[
+				"Path in require_once() __DIR__ . '/../bug-12203-sure-does-not-exist.php' is not a file or it does not exist.",
+				6,
+			],
+		]);
+	}
+
+	public function testInFileExists(): void
+	{
+		$this->analyse([__DIR__ . '/data/include-in-file-exists.php'], []);
+	}
+
+}
diff --git a/tests/PHPStan/Rules/Keywords/RequireFileExistsRuleTest.php b/tests/PHPStan/Rules/Keywords/RequireFileExistsRuleTest.php
index 732819b506..ee7835c51a 100644
--- a/tests/PHPStan/Rules/Keywords/RequireFileExistsRuleTest.php
+++ b/tests/PHPStan/Rules/Keywords/RequireFileExistsRuleTest.php
@@ -2,13 +2,13 @@
 
 namespace PHPStan\Rules\Keywords;
 
+use PHPStan\Node\Printer\ExprPrinter;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
 use function get_include_path;
 use function implode;
 use function realpath;
 use function set_include_path;
-use const DIRECTORY_SEPARATOR;
 use const PATH_SEPARATOR;
 
 /**
@@ -21,7 +21,10 @@ class RequireFileExistsRuleTest extends RuleTestCase
 
 	protected function getRule(): Rule
 	{
-		return new RequireFileExistsRule($this->currentWorkingDirectory);
+		return new RequireFileExistsRule(
+			$this->currentWorkingDirectory,
+			self::getContainer()->getByType(ExprPrinter::class),
+		);
 	}
 
 	public static function getAdditionalConfigFiles(): array
@@ -130,10 +133,15 @@ public function testBug12203(): void
 				5,
 			],
 			[
-				'Path in require_once() "' . __DIR__ . DIRECTORY_SEPARATOR . 'data/../bug-12203-sure-does-not-exist.php" is not a file or it does not exist.',
+				"Path in require_once() __DIR__ . '/../bug-12203-sure-does-not-exist.php' is not a file or it does not exist.",
 				6,
 			],
 		]);
 	}
 
+	public function testInFileExists(): void
+	{
+		$this->analyse([__DIR__ . '/data/include-in-file-exists.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Keywords/data/include-in-file-exists.php b/tests/PHPStan/Rules/Keywords/data/include-in-file-exists.php
new file mode 100644
index 0000000000..74e271d330
--- /dev/null
+++ b/tests/PHPStan/Rules/Keywords/data/include-in-file-exists.php
@@ -0,0 +1,9 @@
+<?php
+
+if (file_exists(__DIR__ . '/../vendor/autoload.php')) {
+	require __DIR__ . '/../vendor/autoload.php';
+}
+
+if (is_file(__DIR__ . '/../vendor/autoload.php')) {
+	require __DIR__ . '/../vendor/autoload.php';
+}