diff --git a/ext/digest/defs.h b/ext/digest/defs.h
new file mode 100644
index 0000000000..7af8f52324
--- /dev/null
+++ b/ext/digest/defs.h
@@ -0,0 +1,34 @@
+/* -*- C -*-
+ * $Id$
+ */
+
+#ifndef DEFS_H
+#define DEFS_H
+
+#include "ruby.h"
+#include <sys/types.h>
+
+#if defined(HAVE_SYS_CDEFS_H)
+# include <sys/cdefs.h>
+#else
+# define __BEGIN_DECLS
+# define __END_DECLS
+#endif
+
+#if defined(HAVE_INTTYPES_H)
+# include <inttypes.h>
+#else
+  typedef unsigned char uint8_t;
+  typedef unsigned int  uint32_t;
+# if SIZEOF_LONG == 8
+  typedef unsigned long uint64_t;
+# elif defined(__GNUC__)
+  typedef unsigned long long uint64_t;
+# elif defined(_MSC_VER)
+  typedef unsigned _int64 uint64_t;
+# else
+#  define NO_UINT64_T
+# endif
+#endif
+
+#endif /* DEFS_H */
diff --git a/ext/digest/md5/extconf.rb b/ext/digest/md5/extconf.rb
new file mode 100644
index 0000000000..93a14025d0
--- /dev/null
+++ b/ext/digest/md5/extconf.rb
@@ -0,0 +1,19 @@
+# $RoughId: extconf.rb,v 1.3 2001/08/14 19:54:51 knu Exp $
+# $Id$
+
+require "mkmf"
+
+$CFLAGS << " -DHAVE_CONFIG_H -I#{File.dirname(__FILE__)}/.."
+
+$objs = [
+  "md5.#{$OBJEXT}",
+  "md5init.#{$OBJEXT}",
+]
+
+have_header("sys/cdefs.h")
+
+have_header("inttypes.h")
+
+have_header("unistd.h")
+
+create_makefile("digest/md5")
diff --git a/ext/digest/rmd160/extconf.rb b/ext/digest/rmd160/extconf.rb
new file mode 100644
index 0000000000..ce53c77b55
--- /dev/null
+++ b/ext/digest/rmd160/extconf.rb
@@ -0,0 +1,20 @@
+# $RoughId: extconf.rb,v 1.3 2001/08/14 19:54:51 knu Exp $
+# $Id$
+
+require "mkmf"
+
+$CFLAGS << " -DHAVE_CONFIG_H -I#{File.dirname(__FILE__)}/.."
+
+$objs = [
+  "rmd160.#{$OBJEXT}",
+  "rmd160hl.#{$OBJEXT}",
+  "rmd160init.#{$OBJEXT}",
+]
+
+have_header("sys/cdefs.h")
+
+have_header("inttypes.h")
+
+have_header("unistd.h")
+
+create_makefile("digest/rmd160")
diff --git a/ext/digest/sha1/extconf.rb b/ext/digest/sha1/extconf.rb
new file mode 100644
index 0000000000..45e374e369
--- /dev/null
+++ b/ext/digest/sha1/extconf.rb
@@ -0,0 +1,20 @@
+# $RoughId: extconf.rb,v 1.3 2001/08/14 19:54:51 knu Exp $
+# $Id$
+
+require "mkmf"
+
+$CFLAGS << " -DHAVE_CONFIG_H -I#{File.dirname(__FILE__)}/.."
+
+$objs = [
+  "sha1.#{$OBJEXT}",
+  "sha1hl.#{$OBJEXT}",
+  "sha1init.#{$OBJEXT}",
+]
+
+have_header("sys/cdefs.h")
+
+have_header("inttypes.h")
+
+have_header("unistd.h")
+
+create_makefile("digest/sha1")
diff --git a/ext/digest/sha2/extconf.rb b/ext/digest/sha2/extconf.rb
new file mode 100644
index 0000000000..f593c79111
--- /dev/null
+++ b/ext/digest/sha2/extconf.rb
@@ -0,0 +1,34 @@
+# $RoughId: extconf.rb,v 1.4 2001/08/14 19:54:51 knu Exp $
+# $Id$
+
+require "mkmf"
+
+$CFLAGS << " -DHAVE_CONFIG_H -I#{File.dirname(__FILE__)}/.."
+
+$objs = [
+  "sha2.#{$OBJEXT}",
+  "sha2hl.#{$OBJEXT}",
+  "sha2init.#{$OBJEXT}",
+]
+
+have_header("sys/cdefs.h")
+
+have_header("inttypes.h")
+
+have_header("unistd.h")
+
+if try_run(<<SRC, $defs.join(' '))
+#include "defs.h"
+int main(void) {
+#ifdef NO_UINT64_T
+    return 1;
+#else
+    return 0;
+#endif
+}
+SRC
+then
+  create_makefile("digest/sha2")
+else
+  puts "** Cannot find a 64bit integer type - skipping the SHA2 module."
+end