diff --git a/modules/libpref/src/init/all.js b/modules/libpref/src/init/all.js
index 2ae54c83f5d..e57c37daa81 100644
--- a/modules/libpref/src/init/all.js
+++ b/modules/libpref/src/init/all.js
@@ -1601,11 +1601,13 @@ pref("network.dns.disableIPv6", true);
 # XP_MACOSX
 #endif
 
-#if XP_OS2
+#ifdef XP_OS2
 
 pref("ui.key.menuAccessKeyFocuses", true);
 pref("layout.css.dpi", -1); // max(96dpi, System setting)
 
+pref("font.alias-list", "sans,sans-serif,serif,monospace");
+
 /* Fonts only needs lists if we have a default that might not be available. */
 /* Tms Rmn, Helv and Courier are ALWAYS available on OS/2 */
 
@@ -1787,7 +1789,7 @@ pref("network.dns.disableIPv6", true);
 # OS2
 #endif
 
-#if XP_BEOS
+#ifdef XP_BEOS
 
 pref("layout.css.dpi", -1); // max(96dpi, System setting)