diff --git a/Scripts/Editor/AdvancedGenericMenu.cs b/Scripts/Editor/AdvancedGenericMenu.cs
index 943c52f..a22fa83 100644
--- a/Scripts/Editor/AdvancedGenericMenu.cs
+++ b/Scripts/Editor/AdvancedGenericMenu.cs
@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+#if UNITY_2019_1_OR_NEWER
+using System.Collections.Generic;
 using System.Linq;
 using UnityEditor.IMGUI.Controls;
 using UnityEngine;
@@ -208,4 +209,5 @@ namespace XNodeEditor
                 gmItem.Run();
         }
     }
-}
\ No newline at end of file
+}
+#endif
\ No newline at end of file
diff --git a/Scripts/Editor/NodeEditor.cs b/Scripts/Editor/NodeEditor.cs
index 0f92e61..8522fc0 100644
--- a/Scripts/Editor/NodeEditor.cs
+++ b/Scripts/Editor/NodeEditor.cs
@@ -8,7 +8,7 @@ using Sirenix.OdinInspector.Editor;
 using Sirenix.Utilities;
 using Sirenix.Utilities.Editor;
 #endif
-#if USE_ADVANCED_GENERIC_MENU
+#if UNITY_2019_1_OR_NEWER && USE_ADVANCED_GENERIC_MENU
 using GenericMenu = XNodeEditor.AdvancedGenericMenu;
 #endif
 
diff --git a/Scripts/Editor/NodeEditorAction.cs b/Scripts/Editor/NodeEditorAction.cs
index 106590c..5d8d32b 100644
--- a/Scripts/Editor/NodeEditorAction.cs
+++ b/Scripts/Editor/NodeEditorAction.cs
@@ -4,7 +4,7 @@ using System.Linq;
 using UnityEditor;
 using UnityEngine;
 using XNodeEditor.Internal;
-#if USE_ADVANCED_GENERIC_MENU
+#if UNITY_2019_1_OR_NEWER && USE_ADVANCED_GENERIC_MENU
 using GenericMenu = XNodeEditor.AdvancedGenericMenu;
 #endif
 
diff --git a/Scripts/Editor/NodeEditorGUI.cs b/Scripts/Editor/NodeEditorGUI.cs
index 630ad4a..35b2e2a 100755
--- a/Scripts/Editor/NodeEditorGUI.cs
+++ b/Scripts/Editor/NodeEditorGUI.cs
@@ -4,7 +4,7 @@ using System.Linq;
 using UnityEditor;
 using UnityEngine;
 using XNodeEditor.Internal;
-#if USE_ADVANCED_GENERIC_MENU
+#if UNITY_2019_1_OR_NEWER && USE_ADVANCED_GENERIC_MENU
 using GenericMenu = XNodeEditor.AdvancedGenericMenu;
 #endif
 
diff --git a/Scripts/Editor/NodeEditorReflection.cs b/Scripts/Editor/NodeEditorReflection.cs
index 2069302..d401139 100644
--- a/Scripts/Editor/NodeEditorReflection.cs
+++ b/Scripts/Editor/NodeEditorReflection.cs
@@ -5,7 +5,7 @@ using System.Linq;
 using System.Reflection;
 using UnityEditor;
 using UnityEngine;
-#if USE_ADVANCED_GENERIC_MENU
+#if UNITY_2019_1_OR_NEWER && USE_ADVANCED_GENERIC_MENU
 using GenericMenu = XNodeEditor.AdvancedGenericMenu;
 #endif
 
diff --git a/Scripts/Editor/NodeGraphEditor.cs b/Scripts/Editor/NodeGraphEditor.cs
index 80b1c1f..a304c2c 100644
--- a/Scripts/Editor/NodeGraphEditor.cs
+++ b/Scripts/Editor/NodeGraphEditor.cs
@@ -2,7 +2,7 @@
 using System.Linq;
 using UnityEditor;
 using UnityEngine;
-#if USE_ADVANCED_GENERIC_MENU
+#if UNITY_2019_1_OR_NEWER && USE_ADVANCED_GENERIC_MENU
 using GenericMenu = XNodeEditor.AdvancedGenericMenu;
 #endif