diff --git a/src/ComposerRequireChecker/FileLocator/LocateAllFilesByExtension.php b/src/ComposerRequireChecker/FileLocator/LocateAllFilesByExtension.php
index 36ce93f6..8e07316c 100644
--- a/src/ComposerRequireChecker/FileLocator/LocateAllFilesByExtension.php
+++ b/src/ComposerRequireChecker/FileLocator/LocateAllFilesByExtension.php
@@ -24,6 +24,8 @@ private function filterFilesByExtension(Traversable $files, string $fileExtensio
     {
         $extensionMatcher = '/.*' . preg_quote($fileExtension) . '$/';
 
+        $blacklist = $this->prepareBlacklistPatterns($blacklist);
+
         /* @var $file \SplFileInfo */
         foreach ($files as $file) {
             if ($blacklist && preg_match('{('.implode('|', $blacklist).')}', $file->getPathname())) {
@@ -37,4 +39,19 @@ private function filterFilesByExtension(Traversable $files, string $fileExtensio
             yield $file->getPathname();
         }
     }
+
+    private function prepareBlacklistPatterns(?array $blacklistPaths)
+    {
+        if ($blacklistPaths === null) {
+            return $blacklistPaths;
+        }
+
+        foreach ($blacklistPaths as &$path) {
+            $path = preg_replace('{/+}', '/', preg_quote(trim(strtr($path, '\\', '/'), '/')));
+            $path = str_replace('\\*\\*', '.+?', $path);
+            $path = str_replace('\\*', '[^/]+?', $path);
+        }
+
+        return $blacklistPaths;
+    }
 }
diff --git a/test/ComposerRequireCheckerTest/FileLocator/LocateComposerPackageSourceFilesTest.php b/test/ComposerRequireCheckerTest/FileLocator/LocateComposerPackageSourceFilesTest.php
index 7f057323..32302af6 100644
--- a/test/ComposerRequireCheckerTest/FileLocator/LocateComposerPackageSourceFilesTest.php
+++ b/test/ComposerRequireCheckerTest/FileLocator/LocateComposerPackageSourceFilesTest.php
@@ -145,19 +145,82 @@ public function testFromPsr4WithNestedDirectoryAlternativeDirectorySeparator()
         $this->assertContains($this->root->getChild('src/MyNamespace/MyClassA.php')->url(), $files);
     }
 
-    public function testFromPsr4WithExcludeFromClassmap()
+    /**
+     * @dataProvider provideExcludePattern
+     */
+    public function testFromPsr4WithExcludeFromClassmap(array $excludedPattern, array $expectedFiles)
     {
+        $excludedPatternJson = json_encode($excludedPattern);
+
         vfsStream::create([
-            'composer.json' => '{"autoload": {"psr-4": {"MyNamespace\\\\": "./"}, "exclude-from-classmap": ["/tests/"]}}',
-            'MyClass.php' => '<?php namespace MyNamespace; class MyClass {}',
+            'composer.json' => '{"autoload": {"psr-4": {"MyNamespace\\\\": ""}, "exclude-from-classmap": ' . $excludedPatternJson . '}}',
+            'ClassA.php' => '<?php namespace MyNamespace; class ClassA {}',
             'tests' => [
-                'MyClassTest.php' => '<?php namespace MyNamespace; class MyClassTest {}',
-            ]
+                'ATest.php' => '<?php namespace MyNamespace; class ATest {}',
+            ],
+            'foo' => [
+                'Tests' => [
+                    'BTest.php' => '<?php namespace MyNamespace; class BTest {}',
+                ],
+                'src' => [
+                    'ClassB.php' => '<?php namespace MyNamespace; class ClassB {}',
+                    'Tests' => [
+                        'CTest.php' => '<?php namespace MyNamespace; class CTest {}',
+                    ],
+                ],
+            ],
         ]);
 
         $files = $this->files($this->root->getChild('composer.json')->url());
 
-        $this->assertCount(1, $files);
+        $this->assertCount(count($expectedFiles), $files);
+        foreach ($expectedFiles as $expectedFile) {
+            $this->assertContains($this->root->getChild($expectedFile)->url(), $files);
+        }
+    }
+
+    /**
+     * @return array[]
+     */
+    public function provideExcludePattern(): array
+    {
+        return [
+            'No exclude pattern' => [
+                [],
+                [
+                    'ClassA.php',
+                    'tests/ATest.php',
+                    'foo/Tests/BTest.php',
+                    'foo/src/ClassB.php',
+                    'foo/src/Tests/CTest.php',
+
+                ],
+            ],
+            'Exclude single directory by pattern' => [
+                ['/tests/'],
+                [
+                    'ClassA.php',
+                    'foo/Tests/BTest.php',
+                    'foo/src/ClassB.php',
+                    'foo/src/Tests/CTest.php',
+                ],
+            ],
+            'Exclude all subdirectories by pattern' => [
+                ['/**Tests/'],
+                [
+                    'ClassA.php',
+                    'tests/ATest.php',
+                    'foo/src/ClassB.php',
+                ],
+            ],
+            'Combine multiple patterns' => [
+                ['/tests/', '/**Tests/'],
+                [
+                    'ClassA.php',
+                    'foo/src/ClassB.php',
+                ],
+            ],
+        ];
     }
 
     /**