http://bugs.gentoo.org/504056

--- configure.ac
+++ configure.ac
@@ -38,6 +38,8 @@
 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
 
+PKG_CHECK_MODULES(X11, [x11])
+
 # Check for imlib2
 AC_CHECK_PROGS(imlib2config_cmd, imlib2-config)
 if test x$imlib2config_cmd = "x"; then
--- src/Makefile.am
+++ src/Makefile.am
@@ -1,7 +1,7 @@
 bin_PROGRAMS = hsetroot
 
 AM_CFLAGS = @CFLAGS@ @IMLIB2_CFLAGS@ -Wall
-LIBS = @IMLIB2_LIBS@
+LIBS = @IMLIB2_LIBS@ $(X11_LIBS)
 
 hsetroot_SOURCES = hsetroot.c