diff --git a/Source/Modules/ControllerModules/KeyHandler_Core.swift b/Source/Modules/ControllerModules/KeyHandler_Core.swift
index b0801710..bc25f26d 100644
--- a/Source/Modules/ControllerModules/KeyHandler_Core.swift
+++ b/Source/Modules/ControllerModules/KeyHandler_Core.swift
@@ -188,7 +188,7 @@ class KeyHandler {
         // 這個過程會讓半衰引擎根據當前上下文生成三元圖索引鍵。
         currentUOM.observe(
           walkedAnchors: walkedAnchors, cursorIndex: adjustedCursor, candidate: theCandidate.value,
-          timestamp: NSDate().timeIntervalSince1970
+          timestamp: NSDate().timeIntervalSince1970, saveCallback: { mgrLangModel.saveUserOverrideModelData() }
         )
       }
     }
diff --git a/Source/Modules/LangModelRelated/SubLMs/lmUserOverride.swift b/Source/Modules/LangModelRelated/SubLMs/lmUserOverride.swift
index e08003e4..2a5d9ee6 100644
--- a/Source/Modules/LangModelRelated/SubLMs/lmUserOverride.swift
+++ b/Source/Modules/LangModelRelated/SubLMs/lmUserOverride.swift
@@ -44,7 +44,8 @@ extension vChewing {
       walkedAnchors: [Megrez.NodeAnchor],
       cursorIndex: Int,
       candidate: String,
-      timestamp: Double
+      timestamp: Double,
+      saveCallback: @escaping () -> Void
     ) {
       let key = convertKeyFrom(walkedAnchors: walkedAnchors, cursorIndex: cursorIndex)
       guard !key.isEmpty else { return }
@@ -64,7 +65,7 @@ extension vChewing {
           mutLRUList.removeLast()
         }
         IME.prtDebugIntel("UOM: Observation finished with new observation: \(key)")
-        mgrLangModel.saveUserOverrideModelData()
+        saveCallback()
         return
       }
       if var theNeta = mutLRUMap[key] {
@@ -72,7 +73,7 @@ extension vChewing {
         mutLRUList.insert(theNeta, at: 0)
         mutLRUMap[key] = theNeta
         IME.prtDebugIntel("UOM: Observation finished with existing observation: \(key)")
-        mgrLangModel.saveUserOverrideModelData()
+        saveCallback()
       }
     }
 
@@ -270,13 +271,13 @@ extension vChewing.LMUserOverride {
 
 extension vChewing.LMUserOverride {
   /// 自 LRU 辭典內移除所有的單元圖。
-  public func bleachUnigrams() {
+  public func bleachUnigrams(saveCallback: @escaping () -> Void) {
     for key in mutLRUMap.keys {
       if !key.contains("(),()") { continue }
       mutLRUMap.removeValue(forKey: key)
     }
     resetMRUList()
-    mgrLangModel.saveUserOverrideModelData()
+    saveCallback()
   }
 
   internal func resetMRUList() {
diff --git a/Source/Modules/LangModelRelated/mgrLangModel.swift b/Source/Modules/LangModelRelated/mgrLangModel.swift
index a0f2be83..ed901684 100644
--- a/Source/Modules/LangModelRelated/mgrLangModel.swift
+++ b/Source/Modules/LangModelRelated/mgrLangModel.swift
@@ -492,9 +492,9 @@ enum mgrLangModel {
   static func removeUnigramsFromUserOverrideModel(_ mode: InputMode) {
     switch mode {
       case .imeModeCHS:
-        gUserOverrideModelCHT.bleachUnigrams()
+        gUserOverrideModelCHT.bleachUnigrams(saveCallback: { mgrLangModel.saveUserOverrideModelData() })
       case .imeModeCHT:
-        gUserOverrideModelCHS.bleachUnigrams()
+        gUserOverrideModelCHS.bleachUnigrams(saveCallback: { mgrLangModel.saveUserOverrideModelData() })
       case .imeModeNULL:
         break
     }