diff --git a/Misc/NEWS.d/next/Windows/2024-05-02-09-28-04.gh-issue-115119.cUKMXo.rst b/Misc/NEWS.d/next/Windows/2024-05-02-09-28-04.gh-issue-115119.cUKMXo.rst
new file mode 100644
index 00000000000..74e9b956a0f
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2024-05-02-09-28-04.gh-issue-115119.cUKMXo.rst
@@ -0,0 +1 @@
+Update Windows installer to use libmpdecimal 4.0.0.
diff --git a/Misc/externals.spdx.json b/Misc/externals.spdx.json
index bef0ce7d7e6..58f8e0afd71 100644
--- a/Misc/externals.spdx.json
+++ b/Misc/externals.spdx.json
@@ -48,14 +48,14 @@
       "checksums": [
         {
           "algorithm": "SHA256",
-          "checksumValue": "93118043651ffa33dcaaab445bae4f8929fca25d2d749079b78e97f220c3d8b1"
+          "checksumValue": "338fac3fb8cdd60f406b6326431338756f58a8af94229ffd9bf1e7c2b1ad71ca"
         }
       ],
-      "downloadLocation": "https://github.com/python/cpython-source-deps/archive/refs/tags/mpdecimal-2.5.1.tar.gz",
+      "downloadLocation": "https://github.com/python/cpython-source-deps/archive/refs/tags/mpdecimal-4.0.0.tar.gz",
       "externalRefs": [
         {
           "referenceCategory": "SECURITY",
-          "referenceLocator": "cpe:2.3:a:bytereef:mpdecimal:2.5.1:*:*:*:*:*:*:*",
+          "referenceLocator": "cpe:2.3:a:bytereef:mpdecimal:4.0.0:*:*:*:*:*:*:*",
           "referenceType": "cpe23Type"
         }
       ],
@@ -63,7 +63,7 @@
       "name": "mpdecimal",
       "originator": "Organization: bytereef.org",
       "primaryPackagePurpose": "SOURCE",
-      "versionInfo": "2.5.1"
+      "versionInfo": "4.0.0"
     },
     {
       "SPDXID": "SPDXRef-PACKAGE-openssl",
diff --git a/PCbuild/get_externals.bat b/PCbuild/get_externals.bat
index 8f07c414272..761d3de93b7 100644
--- a/PCbuild/get_externals.bat
+++ b/PCbuild/get_externals.bat
@@ -54,7 +54,7 @@ set libraries=
 set libraries=%libraries%                                       bzip2-1.0.8
 if NOT "%IncludeLibffiSrc%"=="false" set libraries=%libraries%  libffi-3.4.4
 if NOT "%IncludeSSLSrc%"=="false" set libraries=%libraries%     openssl-3.0.13
-set libraries=%libraries%                                       mpdecimal-2.5.1
+set libraries=%libraries%                                       mpdecimal-4.0.0
 set libraries=%libraries%                                       sqlite-3.45.3.0
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tcl-core-8.6.13.1
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tk-8.6.13.1
diff --git a/PCbuild/python.props b/PCbuild/python.props
index 9f8b42d71cd..86fe8531d7d 100644
--- a/PCbuild/python.props
+++ b/PCbuild/python.props
@@ -74,7 +74,7 @@
     <libffiDir Condition="$(libffiDir) == ''">$(ExternalsDir)libffi-3.4.4\</libffiDir>
     <libffiOutDir Condition="$(libffiOutDir) == ''">$(libffiDir)$(ArchName)\</libffiOutDir>
     <libffiIncludeDir Condition="$(libffiIncludeDir) == ''">$(libffiOutDir)include</libffiIncludeDir>
-    <mpdecimalDir Condition="$(mpdecimalDir) == ''">$(ExternalsDir)\mpdecimal-2.5.1\</mpdecimalDir>
+    <mpdecimalDir Condition="$(mpdecimalDir) == ''">$(ExternalsDir)\mpdecimal-4.0.0\</mpdecimalDir>
     <opensslDir Condition="$(opensslDir) == ''">$(ExternalsDir)openssl-3.0.13\</opensslDir>
     <opensslOutDir Condition="$(opensslOutDir) == ''">$(ExternalsDir)openssl-bin-3.0.13\$(ArchName)\</opensslOutDir>
     <opensslIncludeDir Condition="$(opensslIncludeDir) == ''">$(opensslOutDir)include</opensslIncludeDir>