diff --git a/UPGRADING b/UPGRADING
index c9067e02884..a3f6a12f3dc 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -68,6 +68,9 @@ PHP 8.3 UPGRADE NOTES
 3. Changes in SAPI modules
 ========================================
 
+- $_SERVER['SERVER_SOFTWARE'] value from the built-in CLI server changed
+  to make it compliant with RFC3875.
+
 ========================================
 4. Deprecated Functionality
 ========================================
diff --git a/sapi/cli/php_cli_server.c b/sapi/cli/php_cli_server.c
index e59037ac2e8..8ea04137d12 100644
--- a/sapi/cli/php_cli_server.c
+++ b/sapi/cli/php_cli_server.c
@@ -696,7 +696,7 @@ static void sapi_cli_server_register_variables(zval *track_vars_array) /* {{{ */
 		}
 	}
 	{
-		zend_string *tmp = strpprintf(0, "PHP %s Development Server", PHP_VERSION);
+		zend_string *tmp = strpprintf(0, "PHP/%s (Development Server)", PHP_VERSION);
 		sapi_cli_server_register_known_var_str(track_vars_array, "SERVER_SOFTWARE", strlen("SERVER_SOFTWARE"), tmp);
 		zend_string_release_ex(tmp, /* persistent */ false);
 	}
diff --git a/sapi/cli/tests/php_cli_server_002.phpt b/sapi/cli/tests/php_cli_server_002.phpt
index 2daf6aad731..d2b561b8bb6 100644
--- a/sapi/cli/tests/php_cli_server_002.phpt
+++ b/sapi/cli/tests/php_cli_server_002.phpt
@@ -14,7 +14,7 @@ var_dump(file_get_contents("http://" . PHP_CLI_SERVER_ADDRESS));
 ?>
 --EXPECTF--
 string(%d) "string(%d) "%sphp_cli_server_002"
-string(%d) "PHP %s Development Server"
+string(%d) "PHP/%s (Development Server)"
 string(%d) "localhost"
 string(%d) "%s"
 "