diff --git a/src/include/catalog/duplicate_oids b/src/include/catalog/duplicate_oids
index 0d7aa15559b..072fc00c704 100755
--- a/src/include/catalog/duplicate_oids
+++ b/src/include/catalog/duplicate_oids
@@ -1,11 +1,31 @@
 #!/usr/bin/perl
-
-use lib '../../backend/catalog/';
-use Catalog;
+#----------------------------------------------------------------------
+#
+# duplicate_oids
+#    Identifies any manually-assigned OIDs that are used multiple times
+#    in the Postgres catalog data.
+#
+#    While duplicate OIDs would only cause a failure if they appear in
+#    the same catalog, our project policy is that manually assigned OIDs
+#    should be globally unique, to avoid confusion.
+#
+# Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
+# Portions Copyright (c) 1994, Regents of the University of California
+#
+# src/include/catalog/duplicate_oids
+#
+#----------------------------------------------------------------------
 
 use strict;
 use warnings;
 
+# Must run in src/include/catalog
+use FindBin;
+chdir $FindBin::RealBin or die "could not cd to $FindBin::RealBin: $!\n";
+
+use lib "$FindBin::RealBin/../../backend/catalog/";
+use Catalog;
+
 my @input_files = (glob("pg_*.h"), qw(indexing.h toasting.h));
 
 my $oids = Catalog::FindAllOidsFromHeaders(@input_files);
diff --git a/src/include/catalog/unused_oids b/src/include/catalog/unused_oids
index a727225abcb..2780de052c9 100755
--- a/src/include/catalog/unused_oids
+++ b/src/include/catalog/unused_oids
@@ -1,26 +1,33 @@
 #!/usr/bin/perl
+#----------------------------------------------------------------------
 #
 # unused_oids
+#    Finds blocks of manually-assignable OIDs that have not already been
+#    claimed by previous hackers.  The main use is for finding available
+#    OIDs for new internal functions.  The numbers printed are inclusive
+#    ranges of unused OIDs.
+#
+#    Before using a large empty block, make sure you aren't about
+#    to take over what was intended as expansion space for something
+#    else.
+#
+# Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
+# Portions Copyright (c) 1994, Regents of the University of California
 #
 # src/include/catalog/unused_oids
 #
-#	finds blocks of manually-assignable oids that have not already been
-#	claimed by post_hackers.  primarily useful for finding available
-#	oids for new internal functions.  the numbers printed are inclusive
-#	ranges of unused oids.
-#
-#	before using a large empty block, make sure you aren't about
-#	to take over what was intended as expansion space for something
-#	else.
-#
-#	run this script in src/include/catalog.
-#
-use lib '../../backend/catalog/';
-use Catalog;
+#----------------------------------------------------------------------
 
 use strict;
 use warnings;
 
+# Must run in src/include/catalog
+use FindBin;
+chdir $FindBin::RealBin or die "could not cd to $FindBin::RealBin: $!\n";
+
+use lib "$FindBin::RealBin/../../backend/catalog/";
+use Catalog;
+
 my @input_files = (glob("pg_*.h"), qw(indexing.h toasting.h));
 
 my $oids = Catalog::FindAllOidsFromHeaders(@input_files);
@@ -45,10 +52,5 @@ foreach my $oid (sort { $a <=> $b } @{$oids})
 			printf "%d\n", $prev_oid + 1;
 		}
 	}
-	elsif ($oid == $prev_oid)
-	{
-		print "Duplicate oid detected: $oid\n";
-		exit 1;
-	}
 	$prev_oid = $oid;
 }