diff --git a/IkiWiki/Plugin/aggregate.pm b/IkiWiki/Plugin/aggregate.pm
index b3d4a5eec..9da619375 100644
--- a/IkiWiki/Plugin/aggregate.pm
+++ b/IkiWiki/Plugin/aggregate.pm
@@ -113,6 +113,49 @@ sub launchaggregation () { #{{{
 	return 1;
 } #}}}
 
+sub migrate_to_internal { #{{{
+
+	if (! lockaggregate()) {
+		error("an aggregation process is already running");
+		return;
+	}
+
+	IkiWiki::lockwiki();
+	loadstate();
+
+	foreach my $data (values %guids) {
+		next unless $data->{page};
+
+		$config{aggregateinternal} = 0;
+		my $oldname = pagefile($data->{page});
+
+		$config{aggregateinternal} = 1;
+		my $newname = pagefile($data->{page});
+
+		print "I: $oldname -> $newname\n";
+		if (-e $newname) {
+			if (-e $oldname) {
+				error("$newname already exists");
+			}
+			else {
+				print STDERR 
+					"W: already renamed to $newname?\n";
+			}
+		}
+		elsif (-e $oldname) {
+			rename($oldname, $newname) || error("$!");
+		}
+		else {
+			print "W: $oldname not found\n";
+		}
+	}
+
+	savestate();
+	IkiWiki::unlockwiki;
+
+	unlockaggregate();
+} #}}}
+
 sub needsbuild (@) { #{{{
 	my $needsbuild=shift;
 	
diff --git a/ikiwiki-transition b/ikiwiki-transition
index ce081fe63..6524297ee 100755
--- a/ikiwiki-transition
+++ b/ikiwiki-transition
@@ -99,12 +99,25 @@ sub hashpassword {
 	}
 }
 
+sub aggregateinternal {
+	$config{srcdir} = shift;
+	$config{wikistatedir} = $config{srcdir}."/.ikiwiki";
+	$config{htmlext} = (shift or "html");
+
+	require IkiWiki::Plugin::aggregate;
+
+	IkiWiki::Plugin::aggregate::migrate_to_internal();
+
+	print "... now add aggregateinternal => 1 to your .setup file\n";
+}
+
 sub usage {
 	print STDERR "Usage: ikiwiki-transition type ...\n";
 	print STDERR "Currently supported transition subcommands:\n";
 	print STDERR "	prefix_directives file\n";
 	print STDERR "	indexdb srcdir\n";
 	print STDERR "	hashpassword srcdir\n";
+	print STDERR "	aggregateinternal srcdir [htmlext]\n";
 	exit 1;
 }
 
@@ -120,6 +133,9 @@ elsif ($mode eq 'hashpassword') {
 elsif ($mode eq 'indexdb') {
 	indexdb(@ARGV);
 }
+elsif ($mode eq 'aggregateinternal') {
+	aggregateinternal(@ARGV);
+}
 else {
 	usage();
 }