diff --git a/ChangeLog b/ChangeLog
index 568aeee39..de71ad8bc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2004-01-09  Alexandre Duret-Lutz  <adl@src.lip6.fr>
 
+	* m4/gspnlib.m4 (AX_CHECK_GSPNLIB): Do not warn about a missing
+	library for eesrg.  Define the WITH_GSPN_EESRG conditional.
+	* iface/gspn/Makefile.am (gspn_HEADERS, check_PROGRAMS): Add the
+	eesrg items in condition WITH_GSPN_EESRG.
+	(libspotgspneesrg_la_LIBADD, libspotgspneesrg_la_CPPFLAGS)
+	(libspotgspneesrg_la_SOURCES): Define only in condition
+	WITH_GSPN_EESRG.
+
 	* src/tgbaalgos/emptinesscheck.cc (emptiness_check::print_stats):
 	New function.
 	* src/tgbaalgos/emptinesscheck.hh (emptiness_check::print_stats):
diff --git a/iface/gspn/Makefile.am b/iface/gspn/Makefile.am
index 9280bce6f..c00dbb327 100644
--- a/iface/gspn/Makefile.am
+++ b/iface/gspn/Makefile.am
@@ -1,4 +1,4 @@
-## Copyright (C) 2003  Laboratoire d'Informatique de Paris 6 (LIP6),
+## Copyright (C) 2003, 2004  Laboratoire d'Informatique de Paris 6 (LIP6),
 ## département Systèmes Répartis Coopératifs (SRC), Université Pierre
 ## et Marie Curie.
 ##
@@ -26,8 +26,7 @@ gspndir = $(pkgincludedir)/gspn
 
 gspn_HEADERS = \
   common.hh \
-  gspn.hh \
-  eesrg.hh
+  gspn.hh
 
 lib_LTLIBRARIES = libspotgspn.la libspotgspneesrg.la
 libspotgspn_la_LIBADD = $(top_builddir)/src/libspot.la
@@ -35,19 +34,25 @@ libspotgspn_la_SOURCES = \
   common.cc \
   gspn.cc
 
+check_PROGRAMS = \
+  dottygspn-rg \
+  dottygspn-srg \
+  ltlgspn-rg \
+  ltlgspn-srg
+
+if WITH_GSPN_EESRG
+gspn_HEADERS += eesrg.hh
+check_PROGRAMS += \
+  dottygspn-eesrg \
+  ltleesrg
+
 libspotgspneesrg_la_LIBADD = $(top_builddir)/src/libspot.la
 libspotgspneesrg_la_CPPFLAGS = -DESYMBOLIC $(AM_CPPFLAGS)
 libspotgspneesrg_la_SOURCES = \
   common.cc \
   eesrg.cc
+endif
 
-check_PROGRAMS = \
-  dottygspn-rg \
-  dottygspn-srg \
-  dottygspn-eesrg \
-  ltlgspn-rg \
-  ltlgspn-srg \
-  ltleesrg
 
 dottygspn_rg_SOURCES = dottygspn.cc
 dottygspn_rg_LDADD = libspotgspn.la $(LIBGSPNRG_LDFLAGS)
diff --git a/m4/gspnlib.m4 b/m4/gspnlib.m4
index 8aab6f469..07b63b8f2 100644
--- a/m4/gspnlib.m4
+++ b/m4/gspnlib.m4
@@ -2,11 +2,11 @@ AC_DEFUN([AX_CHECK_GSPNLIB], [
   AC_ARG_WITH([gspn],
 	      [AC_HELP_STRING([--with-gpsn=/root/of/greatspn],
 			      [build interface with GreadSPN])])
-  if test x${with_gspn-no} != xno; then
+  if test "x${with_gspn-no}" != xno; then
     ax_tmp_LDFLAGS=$LDFLAGS
     ax_tmp_LIBS=$LIBS
     LIBGSPN_LDFLAGS=
-    if test x${with_gspn-yes} != xyes; then
+    if test "x${with_gspn-yes}" != xyes; then
        # Try to locate the headers and libraries.
        gspn_version_sh=$with_gspn/SOURCES/contrib/version.sh;
        AC_CHECK_FILE($gspn_version_sh,,
@@ -27,13 +27,16 @@ AC_DEFUN([AX_CHECK_GSPNLIB], [
      LIBGSPNSRG_LDFLAGS="$LIBGSPN_LDFLAGS -lgspnSRG -lm -lfl"
 
      LDFLAGS="$LDFLAGS $LIBGSPN_LDFLAGS"
-     AC_CHECK_LIB([gspnESRG], [initialize], [],
-	[AC_MSG_ERROR([Cannot find libgspnESRG.  Check --with-gspn's argument.])],        [-lm -lfl])
+     # Soheib Baarir is working on this library, and it is not part
+     # of the GreatSPN repository yet.  Use it only if it is here.
+     AC_CHECK_LIB([gspnESRG], [initialize], [have_eesrg=yes],
+	          [have_eesrg=no], [-lm -lfl])
      LIBGSPNESRG_LDFLAGS="$LIBGSPN_LDFLAGS -lgspnESRG -lm -lfl"
      LDFLAGS="$ax_tmp_LDFLAGS"
      LIBS="$ax_tmp_LIBS"
   fi
-  AM_CONDITIONAL([WITH_GSPN], [test x${with_gspn+set} = xset])
+  AM_CONDITIONAL([WITH_GSPN], [test "x${with_gspn-no}" != xno])
+  AM_CONDITIONAL([WITH_GSPN_EESRG], [test "x${have_eesrg-no}" != xno])
   AC_SUBST([LIBGSPN_CPPFLAGS])
   AC_SUBST([LIBGSPNRG_LDFLAGS])
   AC_SUBST([LIBGSPNSRG_LDFLAGS])