--- gtk2-engines-xfce-2.99.2.orig/configure.in
+++ gtk2-engines-xfce-2.99.2/configure.in
@@ -67,6 +67,9 @@ dnl *** Check for optional packages ***
 dnl ***********************************
 XDT_CHECK_OPTIONAL_PACKAGE([GTK2], [gtk+-2.0], [2.20.0], [gtk2], [Gtk 2 theme engine])
 XDT_CHECK_OPTIONAL_PACKAGE([GTK3], [gtk+-3.0], [3.0.0], [gtk3], [Gtk 3 theme engine])
+dnl libm is needed for floor() and ceil()
+AC_CHECK_LIBM
+AC_SUBST(LIBM)
 
 GTK_SUBDIRS=""
 if test x"$GTK2_FOUND" = x"yes"
@@ -80,9 +83,6 @@ then
   GTK3_BINARY_VERSION=`$PKG_CONFIG --variable=gtk_binary_version gtk+-3.0`
   AC_SUBST([GTK3_BINARY_VERSION])
   GTK_SUBDIRS="$GTK_SUBDIRS gtk-3.0"
-  dnl libm is needed for floor() and ceil()
-  AC_CHECK_LIBM
-  AC_SUBST(LIBM)
 fi
 AC_SUBST([GTK_SUBDIRS])
 
--- gtk2-engines-xfce-2.99.2.orig/gtk-2.0/Makefile.am
+++ gtk2-engines-xfce-2.99.2/gtk-2.0/Makefile.am
@@ -30,7 +30,8 @@ libxfce_la_CFLAGS = \
 libxfce_la_LIBADD = \
 	$(GTK2_LIBS) \
 	$(GLIB_LIBS) \
-	$(GMODULE_LIBS)
+	$(GMODULE_LIBS) \
+	$(LIBM)
 
 libxfce_la_LDFLAGS = \
 	-module \