diff --git a/configure b/configure
index b91de5909f..0eb8a3ec07 100755
--- a/configure
+++ b/configure
@@ -18494,7 +18494,8 @@ fi
 
 
 
-for ac_func in cbrt dlopen fcvt fdatasync getifaddrs getpeereid getpeerucred getrlimit memmove poll pstat readlink setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs
+
+for ac_func in cbrt dlopen fcvt fdatasync getifaddrs getpeereid getpeerucred getrlimit memmove poll pstat readlink scandir setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs
 do
 as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 { $as_echo "$as_me:$LINENO: checking for $ac_func" >&5
diff --git a/configure.in b/configure.in
index a57ae37ea3..b733e5f9fb 100644
--- a/configure.in
+++ b/configure.in
@@ -1,5 +1,5 @@
 dnl Process this file with autoconf to produce a configure script.
-dnl $PostgreSQL: pgsql/configure.in,v 1.626 2010/04/30 03:16:58 scrappy Exp $
+dnl $PostgreSQL: pgsql/configure.in,v 1.627 2010/05/13 22:07:42 tgl Exp $
 dnl
 dnl Developers, please strive to achieve this order:
 dnl
@@ -1167,7 +1167,7 @@ PGAC_VAR_INT_TIMEZONE
 AC_FUNC_ACCEPT_ARGTYPES
 PGAC_FUNC_GETTIMEOFDAY_1ARG
 
-AC_CHECK_FUNCS([cbrt dlopen fcvt fdatasync getifaddrs getpeereid getpeerucred getrlimit memmove poll pstat readlink setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs])
+AC_CHECK_FUNCS([cbrt dlopen fcvt fdatasync getifaddrs getpeereid getpeerucred getrlimit memmove poll pstat readlink scandir setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs])
 
 AC_REPLACE_FUNCS(fseeko)
 case $host_os in
diff --git a/contrib/pg_upgrade/file.c b/contrib/pg_upgrade/file.c
index a7aeda93f8..80645bdf54 100644
--- a/contrib/pg_upgrade/file.c
+++ b/contrib/pg_upgrade/file.c
@@ -33,7 +33,7 @@ static int	win32_pghardlink(const char *src, const char *dst);
 static int	copy_dir(const char *from, const char *to, bool force);
 #endif
 
-#if defined(sun) || defined(WIN32)
+#ifndef HAVE_SCANDIR
 static int pg_scandir_internal(migratorContext *ctx, const char *dirname,
 					struct dirent *** namelist,
 					int (*selector) (const struct dirent *));
@@ -235,26 +235,25 @@ copy_file(const char *srcfile, const char *dstfile, bool force)
  * pg_scandir()
  *
  * Wrapper for portable scandir functionality
- *
  */
 int
 pg_scandir(migratorContext *ctx, const char *dirname,
 		   struct dirent ***namelist,
 		   int (*selector) (const struct dirent *))
 {
-#if defined(sun) || defined(WIN32)
+#ifndef HAVE_SCANDIR
 	return pg_scandir_internal(ctx, dirname, namelist, selector);
 
 	/*
+	 * scandir() is originally from BSD 4.3, which had the third argument as
+	 * non-const. Linux and other C libraries have updated it to use a const.
+	 * http://unix.derkeiler.com/Mailing-Lists/FreeBSD/questions/2005-12/msg00214.html
+	 *
 	 * Here we try to guess which libc's need const, and which don't. The net
-	 * goal here is to try to supress a compiler warning due to a prototype
+	 * goal here is to try to suppress a compiler warning due to a prototype
 	 * mismatch of const usage. Ideally we would do this via autoconf, but
-	 * Postgres's autoconf doesn't test for this and it is overkill to add
-	 * autoconf just for this. scandir() is from BSD 4.3, which had the third
-	 * argument as non-const. Linux and other C libraries have updated it to
-	 * use a const.
-	 * http://unix.derkeiler.com/Mailing-Lists/FreeBSD/questions/2005-12/msg002
-	 * 14.html
+	 * autoconf doesn't have a suitable builtin test and it seems overkill
+	 * to add one just to avoid a warning.
 	 */
 #elif defined(freebsd) || defined(bsdi) || defined(darwin) || defined(openbsd)
 	/* no const */
@@ -266,19 +265,18 @@ pg_scandir(migratorContext *ctx, const char *dirname,
 }
 
 
-#if defined(sun) || defined(WIN32)
+#ifndef HAVE_SCANDIR
 /*
  * pg_scandir_internal()
  *
- * We'll provide our own scandir function for sun, since it is not
- * part of the standard system library.
+ * Implement our own scandir() on platforms that don't have it.
  *
  * Returns count of files that meet the selection criteria coded in
  * the function pointed to by selector.  Creates an array of pointers
  * to dirent structures.  Address of array returned in namelist.
  *
  * Note that the number of dirent structures needed is dynamically
- * allocated using realloc.  Realloc can be inneficient if invoked a
+ * allocated using realloc.  Realloc can be inefficient if invoked a
  * large number of times.  Its use in pg_upgrade is to find filesystem
  * filenames that have extended beyond the initial segment (file.1,
  * .2, etc.) and should therefore be invoked a small number of times.
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 684aed4a9f..a54cae309b 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -409,6 +409,9 @@
 /* Define to 1 if you have the `rl_filename_completion_function' function. */
 #undef HAVE_RL_FILENAME_COMPLETION_FUNCTION
 
+/* Define to 1 if you have the `scandir' function. */
+#undef HAVE_SCANDIR
+
 /* Define to 1 if you have the <security/pam_appl.h> header file. */
 #undef HAVE_SECURITY_PAM_APPL_H