diff --git a/IkiWiki/Plugin/aggregate.pm b/IkiWiki/Plugin/aggregate.pm
index 2e4026757..23428cb0e 100644
--- a/IkiWiki/Plugin/aggregate.pm
+++ b/IkiWiki/Plugin/aggregate.pm
@@ -35,11 +35,13 @@ sub getopt () { #{{{
 } #}}}
 
 sub checkconfig () { #{{{
-	loadstate();
 	if ($IkiWiki::config{aggregate}) {
+		IkiWiki::lockwiki();
+		loadstate();
 		IkiWiki::loadindex();
 		aggregate();
 		savestate();
+		IkiWiki::unlockwiki();
 	}
 } #}}}
 
diff --git a/debian/changelog b/debian/changelog
index 70a598599..e89a57cb1 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,8 +1,9 @@
 ikiwiki (1.19) UNRELEASED; urgency=low
 
   * Fix several related bugs in page type determination during online editing.
+  * Add some locking to prevent 2 aggregators from running at once.
 
- -- Joey Hess <joeyh@debian.org>  Sun, 13 Aug 2006 01:53:02 -0400
+ -- Joey Hess <joeyh@debian.org>  Wed, 16 Aug 2006 13:28:34 -0400
 
 ikiwiki (1.18) unstable; urgency=low