diff --git a/Editor/BuildProcess/ObfuzProcess2021.cs b/Editor/BuildProcess/ObfuzProcess2021.cs
index a9913c8..8fe96c7 100644
--- a/Editor/BuildProcess/ObfuzProcess2021.cs
+++ b/Editor/BuildProcess/ObfuzProcess2021.cs
@@ -94,7 +94,7 @@ namespace Obfuz
 #endif
                     Path.Combine(applicationContentsPath, "Managed/UnityEngine"),
                    backupPlayerScriptAssembliesPath,
-                },
+                }.Concat(settings.extraAssemblySearchDirs).ToList(),
                 ObfuscationRuleFiles = settings.ruleFiles.ToList(),
                 mappingXmlPath = settings.mappingFile,
                 outputDir = ObfuzSettings.Instance.GetObfuscatedAssemblyOutputDir(buildTarget),
diff --git a/Editor/Settings/ObfuzSettingProvider.cs b/Editor/Settings/ObfuzSettingProvider.cs
index 0fdab45..e551aca 100644
--- a/Editor/Settings/ObfuzSettingProvider.cs
+++ b/Editor/Settings/ObfuzSettingProvider.cs
@@ -31,6 +31,7 @@ namespace Obfuz
         private SerializedProperty _enable;
         private SerializedProperty _mappingFile;
         private SerializedProperty _ruleFiles;
+        private SerializedProperty _extraAssemblySearchDirs;
 
         public ObfuzSettingsProvider() : base("Project/Obfuz", SettingsScope.Project)
         {
@@ -50,6 +51,7 @@ namespace Obfuz
             _enable = _serializedObject.FindProperty("enable");
             _mappingFile = _serializedObject.FindProperty("mappingFile");
             _ruleFiles = _serializedObject.FindProperty("ruleFiles");
+            _extraAssemblySearchDirs = _serializedObject.FindProperty("extraAssemblySearchDirs");
         }
 
         private void OnEditorFocused()
@@ -72,6 +74,7 @@ namespace Obfuz
                 EditorGUILayout.PropertyField(_enable);
                 EditorGUILayout.PropertyField(_mappingFile);
                 EditorGUILayout.PropertyField(_ruleFiles);
+                EditorGUILayout.PropertyField(_extraAssemblySearchDirs);
 
                 if (EditorGUI.EndChangeCheck())
                 {
diff --git a/Editor/Settings/ObfuzSettings.cs b/Editor/Settings/ObfuzSettings.cs
index 7b4a44d..2dc8298 100644
--- a/Editor/Settings/ObfuzSettings.cs
+++ b/Editor/Settings/ObfuzSettings.cs
@@ -18,6 +18,9 @@ namespace Obfuz
         [Tooltip("obfuscation rule files for assemblies")]
         public string[] ruleFiles;
 
+        [Tooltip("extra assembly search dirs")]
+        public string[] extraAssemblySearchDirs;
+
         public string ObfuzRootDir => $"Library/Obfuz";
 
         public string GetObfuscatedAssemblyOutputDir(BuildTarget target)