diff --git a/README.txt b/README.txt
index 4d9a72a21..8022e3c61 100644
--- a/README.txt
+++ b/README.txt
@@ -94,6 +94,13 @@ configure script that modify its behavior:
 	    common to use --prefix=/opt.  You can configure for a non-root
 	    install with --prefix=$HOME.
 
+NOTE FOR AMD64: If you are building on an AMD64 system, you probably
+want to put libraries in a lib64 directory instead of the usual lib
+directory. This is how Linux/AMD64 keeps 64bit libraries segregated
+from 32bit libraries. This is done by configuring like this:
+
+  ./configure libdir64='$(prefix)/lib64'
+
 2.3 (Optional) Testing
 
 To run a simple test before installation, execute
diff --git a/_pli_types.h.in b/_pli_types.h.in
index 6d4ab7f31..5902ea4e3 100644
--- a/_pli_types.h.in
+++ b/_pli_types.h.in
@@ -19,9 +19,36 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: _pli_types.h.in,v 1.1 2003/09/30 01:33:13 steve Exp $"
+#ident "$Id: _pli_types.h.in,v 1.2 2003/10/02 19:33:44 steve Exp $"
 #endif
 
+# undef HAVE_STDINT_H
+
+#ifdef HAVE_STDINT_H
+
+/*
+ * If the host enhironment has the stdint.h header file,
+ * then use that to size our PLI types.
+ */
+
+# include  <stdint.h>
+typedef uint64_t PLI_UINT64;
+typedef int64_t  PLI_INT64;
+typedef uint32_t PLI_UINT32;
+typedef int32_t  PLI_INT32;
+
+typedef signed short   PLI_INT16;
+typedef unsigned short PLI_UINT16;
+typedef signed char    PLI_BYTE8;
+typedef unsigned char  PLI_UBYTE8;
+
+#else
+
+/*
+ * If we do not have the c99 stdint.h header file, then use
+ * configure detenction to guess the pli types ourselves.
+ */
+
 # define SIZEOF_UNSIGNED_LONG_LONG 8
 # define SIZEOF_UNSIGNED_LONG 8
 # define SIZEOF_UNSIGNED 4
@@ -54,9 +81,13 @@ typedef signed short   PLI_INT16;
 typedef unsigned short PLI_UINT16;
 typedef signed char    PLI_BYTE8;
 typedef unsigned char  PLI_UBYTE8;
+#endif
 
 /*
  * $Log: _pli_types.h.in,v $
+ * Revision 1.2  2003/10/02 19:33:44  steve
+ *  Put libraries in libdir64.
+ *
  * Revision 1.1  2003/09/30 01:33:13  steve
  *  Add PLI_UINT64 to _pli_types.h.
  *
diff --git a/configure.in b/configure.in
index 2dd08fe71..c30404ecb 100644
--- a/configure.in
+++ b/configure.in
@@ -50,7 +50,7 @@ AC_SUBST(EXEEXT)
 
 AC_LANG_CPLUSPLUS
 
-AC_CHECK_HEADERS(getopt.h malloc.h libiberty.h iosfwd sys/wait.h)
+AC_CHECK_HEADERS(getopt.h malloc.h stdint.h libiberty.h iosfwd sys/wait.h)
 
 AC_CHECK_LIB(z, gzwrite)
 AC_CHECK_LIB(z, gzwrite, HAVE_LIBZ=yes, HAVE_LIBZ=no)
diff --git a/libveriuser/Makefile.in b/libveriuser/Makefile.in
index a4adcbb5b..e76b60d53 100644
--- a/libveriuser/Makefile.in
+++ b/libveriuser/Makefile.in
@@ -16,7 +16,7 @@
 #    59 Temple Place - Suite 330
 #    Boston, MA 02111-1307, USA
 #
-#ident "$Id: Makefile.in,v 1.27 2003/08/22 04:27:10 steve Exp $"
+#ident "$Id: Makefile.in,v 1.28 2003/10/02 19:33:44 steve Exp $"
 #
 #
 SHELL = /bin/sh
@@ -30,6 +30,7 @@ VPATH = $(srcdir)
 
 bindir = @bindir@
 libdir = @libdir@
+libdir64 = @libdir64@
 includedir = $(prefix)/include
 
 CC = @CC@ -I. -I.. -I$(srcdir) -I$(srcdir)/..
@@ -83,15 +84,15 @@ clean:
 distclean: clean
 	rm -f Makefile config.status config.log config.cache
 
-install:: all installdirs $(libdir)/libveriuser.a
+install:: all installdirs $(libdir64)/libveriuser.a
 
-$(libdir)/libveriuser.a: ./libveriuser.a
-	$(INSTALL_DATA) ./libveriuser.a $(libdir)/libveriuser.a
+$(libdir64)/libveriuser.a: ./libveriuser.a
+	$(INSTALL_DATA) ./libveriuser.a $(libdir64)/libveriuser.a
 
 installdirs: mkinstalldirs
-	$(srcdir)/mkinstalldirs $(includedir) $(libdir)
+	$(srcdir)/mkinstalldirs $(includedir) $(libdir64)
 
 uninstall::
-	rm -f $(libdir)/libveriuser.a
+	rm -f $(libdir64)/libveriuser.a
 
 -include $(patsubst %.o, dep/%.d, $O)
diff --git a/libveriuser/configure.in b/libveriuser/configure.in
index ffc692a8b..4ddd685e0 100644
--- a/libveriuser/configure.in
+++ b/libveriuser/configure.in
@@ -42,4 +42,14 @@ AC_MSG_RESULT($PICFLAG)
 AC_SUBST(EXEEXT)
 AC_SUBST(EXTRALIBS)
 
+# If not otherwise specified, set the libdir64 variable
+# to the same as libdir.
+AC_MSG_CHECKING(for libdir64 path)
+if test x${libdir64} = x
+then
+	libdir64="${libdir}"
+fi
+AC_SUBST(libdir64)
+AC_MSG_RESULT(${libdir64})
+
 AC_OUTPUT(Makefile)
diff --git a/verilog.spec b/verilog.spec
index c047e49df..35b45b429 100644
--- a/verilog.spec
+++ b/verilog.spec
@@ -26,18 +26,14 @@ to the IEEE-1364 standard.
 
 %build
 %ifarch x86_64
-./configure --prefix=/usr --libdir=/usr/lib64
+./configure --prefix=/usr libdir64='$(prefix)/lib64'
 %else
 ./configure --prefix=/usr
 %endif
 make CXXFLAGS=-O
 
 %install
-%ifarch x86_64
-make prefix=$RPM_BUILD_ROOT/usr libdir=$RPM_BUILD_ROOT/usr/lib64 install
-%else
 make prefix=$RPM_BUILD_ROOT/usr install
-%endif
 
 %files
 
@@ -51,18 +47,6 @@ make prefix=$RPM_BUILD_ROOT/usr install
 %attr(-,root,root) /usr/bin/iverilog
 %attr(-,root,root) /usr/bin/iverilog-vpi
 %attr(-,root,root) /usr/bin/vvp
-%ifarch x86_64
-%attr(-,root,root) /usr/lib64/ivl/ivl
-%attr(-,root,root) /usr/lib64/ivl/ivlpp
-%attr(-,root,root) /usr/lib64/ivl/system.vpi
-%attr(-,root,root) /usr/lib64/ivl/cadpli.vpl
-%attr(-,root,root) /usr/lib64/ivl/null.tgt
-%attr(-,root,root) /usr/lib64/ivl/vvp.tgt
-%attr(-,root,root) /usr/lib64/ivl/fpga.tgt
-%attr(-,root,root) /usr/lib64/ivl/iverilog.conf
-%attr(-,root,root) /usr/lib64/libvpi.a
-%attr(-,root,root) /usr/lib64/libveriuser.a
-%else
 %attr(-,root,root) /usr/lib/ivl/ivl
 %attr(-,root,root) /usr/lib/ivl/ivlpp
 %attr(-,root,root) /usr/lib/ivl/system.vpi
@@ -71,6 +55,10 @@ make prefix=$RPM_BUILD_ROOT/usr install
 %attr(-,root,root) /usr/lib/ivl/vvp.tgt
 %attr(-,root,root) /usr/lib/ivl/fpga.tgt
 %attr(-,root,root) /usr/lib/ivl/iverilog.conf
+%ifarch x86_64
+%attr(-,root,root) /usr/lib64/libvpi.a
+%attr(-,root,root) /usr/lib64/libveriuser.a
+%else
 %attr(-,root,root) /usr/lib/libvpi.a
 %attr(-,root,root) /usr/lib/libveriuser.a
 %endif
diff --git a/vvp/Makefile.in b/vvp/Makefile.in
index f27abdc0c..4fb67876a 100644
--- a/vvp/Makefile.in
+++ b/vvp/Makefile.in
@@ -16,7 +16,7 @@
 #    59 Temple Place - Suite 330
 #    Boston, MA 02111-1307, USA
 #
-#ident "$Id: Makefile.in,v 1.53 2003/09/13 00:59:56 steve Exp $"
+#ident "$Id: Makefile.in,v 1.54 2003/10/02 19:33:44 steve Exp $"
 #
 #
 SHELL = /bin/sh
@@ -32,6 +32,8 @@ libdir = @libdir@
 mandir = @mandir@
 includedir = @includedir@
 
+libdir64 = @libdir64@
+
 CC = @CC@
 HOSTCC = @CC@
 CXX = @CXX@ -Wall
@@ -56,7 +58,7 @@ all: dep vvp@EXEEXT@ libvpi.a
 
 clean:
 	rm -f *.o *~ parse.cc parse.cc.output parse.h lexor.cc tables.cc
-	rm -rf dep vvp@EXEEXT@ libvpi.a libvpi.a
+	rm -rf dep vvp@EXEEXT@ libvpi.a
 
 distclean: clean
 	rm -f Makefile config.status config.log config.cache config.h
@@ -138,13 +140,13 @@ Makefile: Makefile.in config.status
 	./config.status
 
 
-install: all installdirs $(bindir)/vvp@EXEEXT@ $(libdir)/libvpi.a $(INSTALL_DOC)
+install: all installdirs $(bindir)/vvp@EXEEXT@ $(libdir64)/libvpi.a $(INSTALL_DOC)
 
 $(bindir)/vvp@EXEEXT@: ./vvp@EXEEXT@
 	$(INSTALL_PROGRAM) ./vvp@EXEEXT@ $(bindir)/vvp@EXEEXT@
 
-$(libdir)/libvpi.a : ./libvpi.a
-	$(INSTALL_DATA) libvpi.a $(libdir)/libvpi.a
+$(libdir64)/libvpi.a : ./libvpi.a
+	$(INSTALL_DATA) libvpi.a $(libdir64)/libvpi.a
 
 $(mandir)/man1/vvp.1: $(srcdir)/vvp.man
 	$(INSTALL_DATA) $(srcdir)/vvp.man $(mandir)/man1/vvp.1
@@ -153,12 +155,12 @@ $(prefix)/vvp.pdf: vvp.pdf
 	$(INSTALL_DATA) vvp.pdf $(prefix)/vvp.pdf
 
 installdirs: $(srcdir)/mkinstalldirs
-	$(srcdir)/mkinstalldirs $(bindir) $(INSTALL_DOCDIR)
+	$(srcdir)/mkinstalldirs $(bindir) $(libdir) $(libdir64) $(INSTALL_DOCDIR)
 
 
 uninstall:
 	rm -f $(bindir)/vvp@EXEEXT@
-	rm -f $(libdir)/libvpi.a
+	rm -f $(libdir64)/libvpi.a
 	rm -f $(mandir)/man1/vvp.1
 
 -include $(patsubst %.o, dep/%.d, $O)
diff --git a/vvp/configure.in b/vvp/configure.in
index be4218b53..68e8cb935 100644
--- a/vvp/configure.in
+++ b/vvp/configure.in
@@ -198,4 +198,14 @@ esac
 AC_SUBST(ident_support)
 AC_MSG_RESULT($ident_support)
 
+# If not otherwise specified, set the libdir64 variable
+# to the same as libdir.
+AC_MSG_CHECKING(for libdir64 path)
+if test x${libdir64} = x
+then
+	libdir64="${libdir}"
+fi
+AC_SUBST(libdir64)
+AC_MSG_RESULT(${libdir64})
+
 AC_OUTPUT(Makefile)