diff --git a/conf/default.conf.php b/conf/default.conf.php
index 621b932639..83d140241d 100644
--- a/conf/default.conf.php
+++ b/conf/default.conf.php
@@ -1303,6 +1303,7 @@ return array(
   // Set the default monospaced font style for users who haven't set a custom
   // style.
   'style.monospace' => '10px "Menlo", "Consolas", "Monaco", monospace',
+  'style.monospace.windows' => '11px "Menlo", "Consolas", "Monaco", monospace',
 
 
 // -- Debugging ------------------------------------------------------------- //
diff --git a/src/applications/config/option/PhabricatorSyntaxHighlightingConfigOptions.php b/src/applications/config/option/PhabricatorSyntaxHighlightingConfigOptions.php
index a62d12bd93..1bae3269d6 100644
--- a/src/applications/config/option/PhabricatorSyntaxHighlightingConfigOptions.php
+++ b/src/applications/config/option/PhabricatorSyntaxHighlightingConfigOptions.php
@@ -103,12 +103,24 @@ final class PhabricatorSyntaxHighlightingConfigOptions
         'style.monospace',
         'string',
         '10px "Menlo", "Consolas", "Monaco", monospace')
+        ->setLocked(true)
         ->setSummary(
           pht("Default monospace font."))
         ->setDescription(
           pht(
             "Set the default monospaced font style for users who haven't set ".
             "a custom style.")),
+      $this->newOption(
+        'style.monospace.windows',
+        'string',
+        '11px "Menlo", "Consolas", "Monaco", monospace')
+        ->setLocked(true)
+        ->setSummary(
+          pht("Default monospace font for clients on Windows."))
+        ->setDescription(
+          pht(
+            "Set the default monospaced font style for users who haven't set ".
+            "a custom style and are using Windows.")),
     );
   }
 
diff --git a/src/view/page/PhabricatorStandardPageView.php b/src/view/page/PhabricatorStandardPageView.php
index 6dc428b8ad..83ffa592d8 100644
--- a/src/view/page/PhabricatorStandardPageView.php
+++ b/src/view/page/PhabricatorStandardPageView.php
@@ -211,24 +211,29 @@ final class PhabricatorStandardPageView extends PhabricatorBarePageView {
 
   protected function getHead() {
     $monospaced = PhabricatorEnv::getEnvConfig('style.monospace');
+    $monospaced_win = PhabricatorEnv::getEnvConfig('style.monospace.windows');
 
     $request = $this->getRequest();
     if ($request) {
       $user = $request->getUser();
       if ($user) {
-        $monospaced = nonempty(
-          $user->loadPreferences()->getPreference(
-            PhabricatorUserPreferences::PREFERENCE_MONOSPACED),
-          $monospaced);
+        $pref = $user->loadPreferences()->getPreference(
+            PhabricatorUserPreferences::PREFERENCE_MONOSPACED);
+        $monospaced = nonempty($pref, $monospaced);
+        $monospaced_win = nonempty($pref, $monospaced_win);
       }
     }
 
     $response = CelerityAPI::getStaticResourceResponse();
 
     return hsprintf(
-      '%s<style type="text/css">.PhabricatorMonospaced { font: %s; }</style>%s',
+      '%s<style type="text/css">'.
+      '.PhabricatorMonospaced { font: %s; } '.
+      '.platform-windows .PhabricatorMonospaced { font: %s; }'.
+      '</style>%s',
       parent::getHead(),
       phutil_safe_html($monospaced),
+      phutil_safe_html($monospaced_win),
       $response->renderSingleResource('javelin-magical-init'));
   }
 
@@ -396,6 +401,14 @@ final class PhabricatorStandardPageView extends PhabricatorBarePageView {
 
     $classes[] = $device_guess;
 
+    if (preg_match('@Windows@', $agent)) {
+      $classes[] = 'platform-windows';
+    } else if (preg_match('@Macintosh@', $agent)) {
+      $classes[] = 'platform-mac';
+    } else if (preg_match('@X11@', $agent)) {
+      $classes[] = 'platform-linux';
+    }
+
     return implode(' ', $classes);
   }