diff --git a/config/ext.json b/config/ext.json
index b4fe1a68f..3134ab7bb 100644
--- a/config/ext.json
+++ b/config/ext.json
@@ -74,6 +74,14 @@
             "qdbm"
         ]
     },
+    "decimal": {
+        "type": "external",
+        "source": "ext-decimal",
+        "arg-type": "custom",
+        "lib-depends": [
+            "libmpdec"
+        ]
+    },
     "deepclone": {
         "type": "external",
         "source": "deepclone",
diff --git a/config/lib.json b/config/lib.json
index 4792a9329..17258b771 100644
--- a/config/lib.json
+++ b/config/lib.json
@@ -528,6 +528,18 @@
             "maxminddb_config.h"
         ]
     },
+    "libmpdec": {
+        "source": "libmpdec",
+        "static-libs-unix": [
+            "libmpdec.a"
+        ],
+        "static-libs-windows": [
+            "libmpdec_a.lib"
+        ],
+        "headers": [
+            "mpdecimal.h"
+        ]
+    },
     "libmemcached": {
         "source": "libmemcached",
         "cpp-library": true,
diff --git a/config/source.json b/config/source.json
index 6b3e465bc..d7224d4d6 100644
--- a/config/source.json
+++ b/config/source.json
@@ -84,6 +84,16 @@
             "path": "COPYING"
         }
     },
+    "ext-decimal": {
+        "type": "ghtagtar",
+        "repo": "php-decimal/ext-decimal",
+        "match": "v2\\.\\d.*",
+        "path": "php-src/ext/decimal",
+        "license": {
+            "type": "file",
+            "path": "LICENSE"
+        }
+    },
     "deepclone": {
         "type": "ghtagtar",
         "repo": "symfony/php-ext-deepclone",
@@ -690,6 +700,14 @@
             "path": "LICENSE"
         }
     },
+    "libmpdec": {
+        "type": "url",
+        "url": "https://www.bytereef.org/software/mpdecimal/releases/mpdecimal-4.0.1.tar.gz",
+        "license": {
+            "type": "file",
+            "path": "COPYRIGHT.txt"
+        }
+    },
     "libmemcached": {
         "type": "ghtagtar",
         "repo": "awesomized/libmemcached",
diff --git a/phpstan.neon b/phpstan.neon
index a8c1c72c5..482f97d78 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -14,6 +14,7 @@ parameters:
     - PHP_OS_FAMILY
   excludePaths:
       analyseAndScan:
+            - ./src/globals/ext-tests/decimal.php
             - ./src/globals/ext-tests/swoole.php
             - ./src/globals/ext-tests/swoole.phpt
             - ./src/globals/test-extensions.php
diff --git a/src/SPC/builder/extension/decimal.php b/src/SPC/builder/extension/decimal.php
new file mode 100644
index 000000000..795bce2d2
--- /dev/null
+++ b/src/SPC/builder/extension/decimal.php
@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\extension;
+
+use SPC\builder\Extension;
+use SPC\store\FileSystem;
+use SPC\util\CustomExt;
+
+#[CustomExt('decimal')]
+class decimal extends Extension
+{
+    // TODO: remove this when https://github.com/php-decimal/ext-decimal/issues/92 is merged
+    public function patchBeforeBuildconf(): bool
+    {
+        FileSystem::replaceFileStr(
+            $this->source_dir . '/php_decimal.c',
+            'zend_module_entry decimal_module_entry',
+            'zend_module_entry php_decimal_module_entry'
+        );
+        FileSystem::replaceFileStr(
+            $this->source_dir . '/config.w32',
+            'ARG_WITH("decimal", "for decimal support", "no");',
+            'ARG_WITH("decimal", "for decimal support",  "no");' . "\n" .
+            'ADD_EXTENSION_DEP("decimal", "json");'
+        );
+        return true;
+    }
+
+    public function getUnixConfigureArg(bool $shared = false): string
+    {
+        return '--enable-decimal --with-libmpdec-path="' . BUILD_ROOT_PATH . '"';
+    }
+
+    public function getWindowsConfigureArg(bool $shared = false): string
+    {
+        return '--with-decimal';
+    }
+}
diff --git a/src/SPC/builder/freebsd/library/libmpdec.php b/src/SPC/builder/freebsd/library/libmpdec.php
new file mode 100644
index 000000000..9fd38eca8
--- /dev/null
+++ b/src/SPC/builder/freebsd/library/libmpdec.php
@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\freebsd\library;
+
+class libmpdec extends BSDLibraryBase
+{
+    use \SPC\builder\unix\library\libmpdec;
+
+    public const NAME = 'libmpdec';
+}
diff --git a/src/SPC/builder/linux/library/libmpdec.php b/src/SPC/builder/linux/library/libmpdec.php
new file mode 100644
index 000000000..594bed4f1
--- /dev/null
+++ b/src/SPC/builder/linux/library/libmpdec.php
@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\linux\library;
+
+class libmpdec extends LinuxLibraryBase
+{
+    use \SPC\builder\unix\library\libmpdec;
+
+    public const NAME = 'libmpdec';
+}
diff --git a/src/SPC/builder/macos/library/libmpdec.php b/src/SPC/builder/macos/library/libmpdec.php
new file mode 100644
index 000000000..18eca254c
--- /dev/null
+++ b/src/SPC/builder/macos/library/libmpdec.php
@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\macos\library;
+
+class libmpdec extends MacOSLibraryBase
+{
+    use \SPC\builder\unix\library\libmpdec;
+
+    public const NAME = 'libmpdec';
+}
diff --git a/src/SPC/builder/unix/library/libmpdec.php b/src/SPC/builder/unix/library/libmpdec.php
new file mode 100644
index 000000000..39b89aef8
--- /dev/null
+++ b/src/SPC/builder/unix/library/libmpdec.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\unix\library;
+
+use SPC\util\executor\UnixAutoconfExecutor;
+
+trait libmpdec
+{
+    protected function build(): void
+    {
+        UnixAutoconfExecutor::create($this)
+            ->configure('--disable-cxx --disable-shared --enable-static')
+            ->make();
+    }
+}
diff --git a/src/SPC/builder/windows/library/libmpdec.php b/src/SPC/builder/windows/library/libmpdec.php
new file mode 100644
index 000000000..3468c58e8
--- /dev/null
+++ b/src/SPC/builder/windows/library/libmpdec.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\windows\library;
+
+class libmpdec extends WindowsLibraryBase
+{
+    public const NAME = 'libmpdec';
+
+    protected function build(): void
+    {
+        $makefile_dir = $this->source_dir . '\libmpdec';
+        $nmake = $this->builder->makeSimpleWrapper('nmake /nologo');
+
+        cmd()->cd($makefile_dir)
+            ->exec('copy /y Makefile.vc Makefile')
+            ->execWithWrapper($nmake, 'clean')
+            ->execWithWrapper($nmake, 'MACHINE=x64');
+
+        // Copy static lib (rename from versioned name to libmpdec_a.lib)
+        $libs = glob($makefile_dir . '\libmpdec-*.lib');
+        foreach ($libs as $lib) {
+            if (!str_contains($lib, '.dll.')) {
+                copy($lib, BUILD_LIB_PATH . '\libmpdec_a.lib');
+                break;
+            }
+        }
+        copy($makefile_dir . '\mpdecimal.h', BUILD_INCLUDE_PATH . '\mpdecimal.h');
+    }
+}
diff --git a/src/globals/ext-tests/decimal.php b/src/globals/ext-tests/decimal.php
new file mode 100644
index 000000000..54f660fbb
--- /dev/null
+++ b/src/globals/ext-tests/decimal.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+assert(class_exists('Decimal\Decimal'));
+assert(method_exists('Decimal\Decimal', 'valueOf'));
+assert(0.1 + 0.2 !== 0.3);
+$result = Decimal\Decimal::valueOf('0.1') + Decimal\Decimal::valueOf('0.2');
+$expected = Decimal\Decimal::valueOf('0.3');
+assert($result == $expected);
diff --git a/src/globals/test-extensions.php b/src/globals/test-extensions.php
index e5c4f6d85..cbcecb0ee 100644
--- a/src/globals/test-extensions.php
+++ b/src/globals/test-extensions.php
@@ -15,7 +15,7 @@
 $test_php_version = [
     // '8.1',
     // '8.2',
-    '8.3',
+    // '8.3',
     // '8.4',
     '8.5',
     // 'git',
@@ -23,13 +23,13 @@
 
 // test os (macos-15-intel, macos-15, ubuntu-latest, windows-latest are available)
 $test_os = [
-    'macos-15-intel', // bin/spc for x86_64
-    'macos-15', // bin/spc for arm64
-    'ubuntu-latest', // bin/spc-alpine-docker for x86_64
-    'ubuntu-22.04', // bin/spc-gnu-docker for x86_64
-    'ubuntu-24.04', // bin/spc for x86_64
-    'ubuntu-22.04-arm', // bin/spc-gnu-docker for arm64
-    'ubuntu-24.04-arm', // bin/spc for arm64
+    // 'macos-15-intel', // bin/spc for x86_64
+    // 'macos-15', // bin/spc for arm64
+    // 'ubuntu-latest', // bin/spc-alpine-docker for x86_64
+    // 'ubuntu-22.04', // bin/spc-gnu-docker for x86_64
+    // 'ubuntu-24.04', // bin/spc for x86_64
+    // 'ubuntu-22.04-arm', // bin/spc-gnu-docker for arm64
+    // 'ubuntu-24.04-arm', // bin/spc for arm64
     'windows-2022', // .\bin\spc.ps1
     'windows-2025',
 ];
@@ -50,8 +50,8 @@
 
 // If you want to test your added extensions and libs, add below (comma separated, example `bcmath,openssl`).
 $extensions = match (PHP_OS_FAMILY) {
-    'Linux', 'Darwin' => 'deepclone',
-    'Windows' => 'deepclone',
+    'Linux', 'Darwin' => 'decimal',
+    'Windows' => 'decimal',
 };
 
 // If you want to test shared extensions, add them below (comma separated, example `bcmath,openssl`).