diff --git a/doc/en/html/about/history.html b/doc/en/html/about/history.html
index 4605c8cd3..594be3490 100644
--- a/doc/en/html/about/history.html
+++ b/doc/en/html/about/history.html
@@ -32,7 +32,7 @@ <h1>History</h1>
 
 <h2 id="teraterm">Tera Term</h2>
 
-<h3 id="teraterm_5.1">YYYY.MM.DD (Ver 5.1, not yet released)</h3>
+<h3 id="teraterm_5.1">2023.12.19 (Ver 5.1)</h3>
 <ul class="history">
   <!-- li>Changes
     <ul>
@@ -3390,7 +3390,7 @@ <h3 id="teraterm_0.0">1994.2.24 (Ver 0.0)</h3>
 
 <h2 id="ttssh">TTSSH</h2>
 
-<h3 id="ttssh_3.1">YYYY.MM.DD (Ver 3.1 not released)</h3>
+<h3 id="ttssh_3.1">2023.12.19 (Ver 3.1)</h3>
 <ul class="history">
   <li>Changes
     <ul>
@@ -5271,7 +5271,7 @@ <h3 id="ttproxy_1.0.0.8">2006.8.1 (Ver 1.0.0.8)</h3>
 
 <h2 id="ttmenu">TeraTerm Menu</h2>
 
-<h3 id="ttmenu_1.18">YYYY.MM.DD (Ver 1.18)</h3>
+<h3 id="ttmenu_1.18">2023.12.19 (Ver 1.18)</h3>
 <ul class="history">
       <li>Win32 API was changed to the Unicode version, and strings were changed to Unicode.
 </ul>
diff --git a/doc/ja/html/about/history.html b/doc/ja/html/about/history.html
index 955187e2d..42df3b1af 100644
--- a/doc/ja/html/about/history.html
+++ b/doc/ja/html/about/history.html
@@ -32,7 +32,7 @@
 
 <h2 id="teraterm">Tera Term</h2>
 
-<h3 id="teraterm_5.1">YYYY.MM.DD (Ver 5.1, not yet released)</h3>
+<h3 id="teraterm_5.1">2023.12.19 (Ver 5.1)</h3>
 <ul class="history">
   <!-- li>変更
     <ul>
@@ -3398,7 +3398,7 @@ <h3 id="teraterm_0.0">1994.2.24 (Ver 0.0)</h3>
 
 <h2 id="ttssh">TTSSH</h2>
 
-<h3 id="ttssh_3.1">YYYY.MM.DD (Ver 3.1 not released)</h3>
+<h3 id="ttssh_3.1">2023.12.19 (Ver 3.1)</h3>
 <ul class="history">
   <li>変更
     <ul>
@@ -5280,7 +5280,7 @@ <h3 id="ttproxy_1.0.0.8">2006.8.1 (Ver 1.0.0.8)</h3>
 
 <h2 id="ttmenu">TeraTerm Menu</h2>
 
-<h3 id="ttmenu_1.18">YYYY.MM.DD (Ver 1.18)</h3>
+<h3 id="ttmenu_1.18">2023.12.19 (Ver 1.18)</h3>
 <ul class="history">
       <li>使用しているWin32 APIを Unicode版に変更、文字列をUnicodeに変更した。</li>
 </ul>
diff --git a/installer/teraterm.iss b/installer/teraterm.iss
index c233fbf53..d215b3be7 100755
--- a/installer/teraterm.iss
+++ b/installer/teraterm.iss
@@ -1,33 +1,33 @@
 �ｻｿ#define AppName "Tera Term"
 #ifndef AppVer
-#define AppVer "5.1-dev"
+#define AppVer "5.1"
 #endif
 ;#define VerSubStr
 ;#define OutputSubStr
 
 [InnoIDE_PreCompile]
 Name: makechm.bat
-Name: build.bat
-;Name: build.bat; Parameters: rebuild
+;Name: build.bat
+Name: build.bat; Parameters: rebuild
 
 [InnoIDE_PostCompile]
-;Name: makearchive.bat; Parameters: release
+Name: makearchive.bat; Parameters: release
 
 [PreCompile]
 Name: makechm.bat
-Name: build.bat
-;Name: build.bat; Parameters: rebuild
+;Name: build.bat
+Name: build.bat; Parameters: rebuild
 
 [PostCompile]
-;Name: makearchive.bat; Parameters: release
+Name: makearchive.bat; Parameters: release
 
 [_ISToolPreCompile]
 Name: makechm.bat
-Name: build.bat
-;Name: build.bat; Parameters: rebuild
+;Name: build.bat
+Name: build.bat; Parameters: rebuild
 
 [_ISToolPostCompile]
-;Name: makearchive.bat; Parameters: release
+Name: makearchive.bat; Parameters: release
 
 [Setup]
 AppCopyright=(C) 2004-2023 TeraTerm Project
diff --git a/teraterm/common/tt-version.h b/teraterm/common/tt-version.h
index a8781033a..a5dbc165e 100644
--- a/teraterm/common/tt-version.h
+++ b/teraterm/common/tt-version.h
@@ -30,8 +30,8 @@
 
 #define TT_VERSION_MAJOR             5
 #define TT_VERSION_MINOR             1
-#define TT_VERSION_SUBSTR            "dev"
-// #undef TT_VERSION_SUBSTR
+// #define TT_VERSION_SUBSTR            "dev"
+#undef TT_VERSION_SUBSTR
 // SUBSTR が不要な時は undef する
 //  使用例 "dev", "RC", "RC2"