diff --git a/src/test/core/Config_test.cpp b/src/test/core/Config_test.cpp
index e3327c8c57..293538990f 100644
--- a/src/test/core/Config_test.cpp
+++ b/src/test/core/Config_test.cpp
@@ -122,6 +122,83 @@ backend=sqlite
     return std::format(kConfigContentsTemplate, dbPathSection, valFileSection);
 }
 
+// setenv and unsetenv are POSIX only, and MSVC does not have them.
+#ifndef _MSC_VER
+
+/**
+ * Read an environment variable into a value the caller owns.
+ *
+ * The value is copied, because POSIX allows a later `setenv` to release the
+ * string `getenv` returned.
+ *
+ * @param name Name of the environment variable to read.
+ * @return The value, or std::nullopt when the variable is not set.
+ */
+[[nodiscard]] std::optional<std::string>
+envVar(char const* name)
+{
+    if (char const* const value = std::getenv(name); value != nullptr)
+        return std::string{value};
+
+    return std::nullopt;
+}
+
+/**
+ * Set an environment variable and restore its previous value when done.
+ */
+class EnvVarGuard
+{
+private:
+    std::string const name_;
+    std::optional<std::string> const saved_;
+
+    /**
+     * Give an environment variable a value, or remove it.
+     *
+     * @param name Name of the environment variable to write.
+     * @param value Value to set, or std::nullopt to remove the variable.
+     */
+    static void
+    apply(char const* name, std::optional<std::string> const& value) noexcept
+    {
+        if (value)
+        {
+            setenv(name, value->c_str(), 1);
+        }
+        else
+        {
+            unsetenv(name);
+        }
+    }
+
+public:
+    /**
+     * Save the variable's current value, then write the given one.
+     *
+     * @param name Name of the environment variable to set.
+     * @param value Value to set, or std::nullopt to remove the variable.
+     */
+    [[nodiscard]] EnvVarGuard(char const* name, std::optional<std::string> const& value)
+        : name_(name), saved_(envVar(name))
+    {
+        apply(name_.c_str(), value);
+    }
+
+    EnvVarGuard(EnvVarGuard const&) = delete;
+    EnvVarGuard&
+    operator=(EnvVarGuard const&) = delete;
+
+    /**
+     * Restore the value the variable held before construction.
+     */
+    ~EnvVarGuard()
+    {
+        apply(name_.c_str(), saved_);
+    }
+};
+
+#endif  // _MSC_VER
+
 /**
  * Write an xrpld config file and remove when done.
  */
@@ -335,7 +412,11 @@ port_wss_admin
         }
 
         // Config file in HOME or XDG_CONFIG_HOME directory.
-#if BOOST_OS_LINUX || BOOST_OS_MACOS
+#ifndef _MSC_VER
+        // Save the values the guards below must put back.
+        auto const home = detail::envVar("HOME");
+        auto const xdgConfigHome = detail::envVar("XDG_CONFIG_HOME");
+
         for (auto const& configFile : configFiles)
         {
             // Point the current working directory to a temporary directory, so
@@ -348,13 +429,11 @@ port_wss_admin
             {
                 TempDir const tc;
 
-                // Set the HOME and XDG_CONFIG_HOME environment variables. The
-                // HOME variable is not used when XDG_CONFIG_HOME is set, but
-                // must be set.
-                char const* h = getenv("HOME");
-                setenv("HOME", tc.path().c_str(), 1);
-                char const* x = getenv("XDG_CONFIG_HOME");
-                setenv("XDG_CONFIG_HOME", tc.path().c_str(), 1);
+                // The HOME variable is not used when XDG_CONFIG_HOME is set,
+                // but must be set. Both guards are declared after tc, so they
+                // restore before it is removed.
+                detail::EnvVarGuard const homeGuard("HOME", tc.path());
+                detail::EnvVarGuard const xdgGuard("XDG_CONFIG_HOME", tc.path());
 
                 // Create the config file in '${XDG_CONFIG_HOME}/[systemName]'.
                 Path p = tc.file(systemName());
@@ -371,22 +450,21 @@ port_wss_admin
                 BEAST_EXPECT(
                     c.section(Sections::kDebugLogfile).values()[0] ==
                     "/Users/dummy/xrpld/config/log/debug.log");
-
-                // Restore the environment variables.
-                (h != nullptr) ? setenv("HOME", h, 1) : unsetenv("HOME");
-                (x != nullptr) ? setenv("XDG_CONFIG_HOME", x, 1) : unsetenv("XDG_CONFIG_HOME");
             }
 
+            // Both guards are gone: both variables must hold their old values.
+            BEAST_EXPECT(detail::envVar("HOME") == home);
+            BEAST_EXPECT(detail::envVar("XDG_CONFIG_HOME") == xdgConfigHome);
+
             // The XDG config directory is not set: the config file must be in a
             // subdirectory named .config followed by the system name.
             {
                 TempDir const tc;
 
-                // Set only the HOME environment variable.
-                char const* h = getenv("HOME");
-                setenv("HOME", tc.path().c_str(), 1);
-                char const* x = getenv("XDG_CONFIG_HOME");
-                unsetenv("XDG_CONFIG_HOME");
+                // Both guards are declared after tc, so they restore before it
+                // is removed.
+                detail::EnvVarGuard const homeGuard("HOME", tc.path());
+                detail::EnvVarGuard const xdgGuard("XDG_CONFIG_HOME", std::nullopt);
 
                 // Create the config file in '${HOME}/.config/[systemName]'.
                 std::string s = ".config";
@@ -407,14 +485,13 @@ port_wss_admin
                 BEAST_EXPECT(
                     c.section(Sections::kDebugLogfile).values()[0] ==
                     "/Users/dummy/xrpld/config/log/debug.log");
-
-                // Restore the environment variables.
-                (h != nullptr) ? setenv("HOME", h, 1) : unsetenv("HOME");
-                if (x != nullptr)
-                    setenv("XDG_CONFIG_HOME", x, 1);
             }
+
+            // Both guards are gone: both variables must hold their old values.
+            BEAST_EXPECT(detail::envVar("HOME") == home);
+            BEAST_EXPECT(detail::envVar("XDG_CONFIG_HOME") == xdgConfigHome);
         }
-#endif
+#endif  // _MSC_VER
 
         // Restore the current working directory.
         current_path(cwd);