diff --git a/Tekkon.Tests/Tekkon.Tests.csproj b/Tekkon.Tests/Tekkon.Tests.csproj
index d385c71..fe9ce91 100644
--- a/Tekkon.Tests/Tekkon.Tests.csproj
+++ b/Tekkon.Tests/Tekkon.Tests.csproj
@@ -4,7 +4,7 @@
     <TargetFramework>net6.0</TargetFramework>
     <Nullable>enable</Nullable>
     <IsPackable>false</IsPackable>
-    <ReleaseVersion>1.5.0</ReleaseVersion>
+    <ReleaseVersion>1.5.1</ReleaseVersion>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/Tekkon.sln b/Tekkon.sln
index ded0584..2f7dec5 100644
--- a/Tekkon.sln
+++ b/Tekkon.sln
@@ -47,6 +47,6 @@ Global
 		$0.DotNetNamingPolicy = $4
 		$4.DirectoryNamespaceAssociation = PrefixedHierarchical
 		$0.StandardHeader = $5
-		version = 1.5.0
+		version = 1.5.1
 	EndGlobalSection
 EndGlobal
diff --git a/Tekkon/Composer.cs b/Tekkon/Composer.cs
index ea55940..e4c1052 100644
--- a/Tekkon/Composer.cs
+++ b/Tekkon/Composer.cs
@@ -176,41 +176,47 @@ public void Clear() {
   /// <returns>傳入的字符是否合規。</returns>
   public bool InputValidityCheck(int inputCharCode) {
     char inputKey = (char)Math.Abs(inputCharCode);
-    if (inputKey >= 128) return false;
-    switch (Parser) {
-      case MandarinParser.OfDachen:
-        return Shared.MapQwertyDachen.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfDachen26:
-        return Shared.MapDachenCp26StaticKeys.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfETen:
-        return Shared.MapQwertyETenTraditional.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfHsu:
-        return Shared.MapHsuStaticKeys.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfETen26:
-        return Shared.MapETen26StaticKeys.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfIBM:
-        return Shared.MapQwertyIBM.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfMiTAC:
-        return Shared.MapQwertyMiTAC.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfSeigyou:
-        return Shared.MapSeigyou.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfFakeSeigyou:
-        return Shared.MapFakeSeigyou.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfStarlight:
-        return Shared.MapStarlightStaticKeys.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfAlvinLiu:
-        return Shared.MapAlvinLiuStaticKeys.ContainsKey(inputKey.ToString());
-      case MandarinParser.OfWadeGilesPinyin:
-        return Shared.MapWadeGilesPinyinKeys.Contains(inputKey);
-      case MandarinParser.OfHanyuPinyin:
-      case MandarinParser.OfSecondaryPinyin:
-      case MandarinParser.OfYalePinyin:
-      case MandarinParser.OfHualuoPinyin:
-      case MandarinParser.OfUniversalPinyin:
-        return Shared.MapArayuruPinyin.Contains(inputKey);
-      default:
-        return false;
-    }
+    return (inputKey < 128) && InputValidityCheckStr(inputKey.ToString());
+  }
+
+  /// <summary>
+  /// 用於檢測「某個輸入字符訊號的合規性」的函式。<br />
+  /// <br />
+  /// 注意：回傳結果會受到當前注音排列 parser 屬性的影響。
+  /// </summary>
+  /// <param name="charStr">傳入的字元（String）。</param>
+  /// <returns>傳入的字符是否合規。</returns>
+  public bool InputValidityCheckStr(string charStr) {
+    return Parser switch {
+      MandarinParser.OfDachen => Shared.MapQwertyDachen.ContainsKey(charStr),
+      MandarinParser.OfDachen26 =>
+          Shared.MapDachenCp26StaticKeys.ContainsKey(charStr),
+      MandarinParser.OfETen =>
+          Shared.MapQwertyETenTraditional.ContainsKey(charStr),
+      MandarinParser.OfHsu => Shared.MapHsuStaticKeys.ContainsKey(charStr),
+      MandarinParser.OfETen26 =>
+          Shared.MapETen26StaticKeys.ContainsKey(charStr),
+      MandarinParser.OfIBM => Shared.MapQwertyIBM.ContainsKey(charStr),
+      MandarinParser.OfMiTAC => Shared.MapQwertyMiTAC.ContainsKey(charStr),
+      MandarinParser.OfSeigyou => Shared.MapSeigyou.ContainsKey(charStr),
+      MandarinParser.OfFakeSeigyou =>
+          Shared.MapFakeSeigyou.ContainsKey(charStr),
+      MandarinParser.OfStarlight =>
+          Shared.MapStarlightStaticKeys.ContainsKey(charStr),
+      MandarinParser.OfAlvinLiu =>
+          Shared.MapAlvinLiuStaticKeys.ContainsKey(charStr),
+      MandarinParser.OfWadeGilesPinyin =>
+          Shared.MapWadeGilesPinyinKeys.Contains(charStr),
+      MandarinParser.OfHanyuPinyin => Shared.MapArayuruPinyin.Contains(charStr),
+      MandarinParser.OfSecondaryPinyin =>
+          Shared.MapArayuruPinyin.Contains(charStr),
+      MandarinParser.OfYalePinyin => Shared.MapArayuruPinyin.Contains(charStr),
+      MandarinParser.OfHualuoPinyin =>
+          Shared.MapArayuruPinyin.Contains(charStr),
+      MandarinParser.OfUniversalPinyin =>
+          Shared.MapArayuruPinyin.Contains(charStr),
+      _ => false
+    };
   }
 
   /// <summary>
diff --git a/Tekkon/Tekkon.csproj b/Tekkon/Tekkon.csproj
index df83833..f0bf3ba 100644
--- a/Tekkon/Tekkon.csproj
+++ b/Tekkon/Tekkon.csproj
@@ -3,16 +3,16 @@
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
     <CodePage>65001</CodePage>
-    <ReleaseVersion>1.5.0</ReleaseVersion>
+    <ReleaseVersion>1.5.1</ReleaseVersion>
     <PackageId>vChewing.Tekkon</PackageId>
     <Authors>Shiki Suen</Authors>
     <Company>Atelier Inmu</Company>
     <Copyright>(c) 2022 and onwards The vChewing Project (MIT-NTL License).</Copyright>
     <RepositoryUrl>https://github.com/ShikiSuen/TekkonNT</RepositoryUrl>
     <NeutralLanguage>zh-TW</NeutralLanguage>
-    <AssemblyVersion>1.5.0</AssemblyVersion>
-    <FileVersion>1.5.0</FileVersion>
-    <Version>1.5.0</Version>
+    <AssemblyVersion>1.5.1</AssemblyVersion>
+    <FileVersion>1.5.1</FileVersion>
+    <Version>1.5.1</Version>
     <Product>Tekkon</Product>
     <GeneratePackageOnBuild>True</GeneratePackageOnBuild>
     <PackageReadmeFile>README.md</PackageReadmeFile>