diff --git a/package/kde/kdelibs/kde-3.conf b/package/kde/kdelibs/kde-3.conf
index 12afc64ea..7812ac829 100644
--- a/package/kde/kdelibs/kde-3.conf
+++ b/package/kde/kdelibs/kde-3.conf
@@ -27,7 +27,8 @@ var_append confopt " " "--with-qt-dir=$QTDIR \
 pkginstalled openldap && var_append confopt ' ' "--with-ldap=$root/$pkg_openldap_prefix"
 var_append confopt " " "--with-xinerama --enable-dnotify"
 
-[ $arch = x86 ] && var_append confopt " " "--enable-fast-malloc=full"
+[ "$arch" = "x86" -a "ROCKCFG_X86_BITS" = "32" ] && \
+	var_append confopt " " "--enable-fast-malloc=full"
 
 # keep .la files in the main packages, kde needs them at runtime
 splitreg 45 . '/.*\.la$'