diff --git a/IkiWiki/Plugin/aggregate.pm b/IkiWiki/Plugin/aggregate.pm
index 0da527f25..09ea59029 100644
--- a/IkiWiki/Plugin/aggregate.pm
+++ b/IkiWiki/Plugin/aggregate.pm
@@ -37,14 +37,25 @@ sub checkconfig () { #{{{
 			debug("wiki is locked by another process, not aggregating");
 			exit 1;
 		}
-	
-		loadstate();
-		IkiWiki::loadindex();
-		aggregate();
-		expire();
-		savestate();
-		clearstate();
-
+		
+		# Fork a child process to handle the aggregation.
+		# The parent process will then handle building the result.
+		# This avoids messy code to clear state accumulated while
+		# aggregating.
+		defined(my $pid = fork) or error("Can’t fork: $!");
+		if (! $pid) {
+			loadstate();
+			IkiWiki::loadindex();
+			aggregate();
+			expire();
+			savestate();
+			exit 0;
+		}
+		waitpid($pid,0);
+		if ($?) {
+			error "aggregation failed with code $?";
+		}
+		
 		IkiWiki::unlockwiki();
 	}
 } #}}}
@@ -211,12 +222,6 @@ sub savestate () { #{{{
 		error("rename $newfile: $!", $cleanup);
 } #}}}
 
-sub clearstate () { #{{{
-	%feeds=();
-	%guids=();
-	$state_loaded=0;
-} #}}}
-
 sub expire () { #{{{
 	foreach my $feed (values %feeds) {
 		next unless $feed->{expireage} || $feed->{expirecount};
diff --git a/debian/changelog b/debian/changelog
index f5e0b242e..d2fed8767 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -5,6 +5,10 @@ ikiwiki (2.21) UNRELEASED; urgency=low
     those older versions too.
   * aggregate: Don't let feeds set creation times for pages in the future.
   * Add full parser for git diff-tree output (Brian Downing)
+  * aggregate: Fork a child process to handle the aggregation. This simplifies
+    the code, since that process can change internal state as needed, and 
+    it will automatically be cleaned up for the parent process, which proceeds
+    to render the changes.
 
  -- Joey Hess <joeyh@debian.org>  Fri, 11 Jan 2008 15:09:37 -0500