diff --git a/IkiWiki/Plugin/polygen.pm b/IkiWiki/Plugin/polygen.pm
index 78e3611e1..8ce62b754 100644
--- a/IkiWiki/Plugin/polygen.pm
+++ b/IkiWiki/Plugin/polygen.pm
@@ -28,6 +28,7 @@ sub preprocess (@) {
 	my %params=@_;
 	my $grammar = ($params{grammar} or 'polygen');
 	my $symbol = ($params{symbol} or undef);
+	my $options = ($config{deterministic} ? '-seed 42' : '');
 
 	# Sanitize parameters
 	$grammar =~ IkiWiki::basename($grammar);
@@ -51,10 +52,10 @@ sub preprocess (@) {
 	
 	my $res;
 	if (defined $symbol) {
-		$res = `polygen -S $symbol $grmfile 2>/dev/null`;
+		$res = `polygen -S $symbol $options $grmfile 2>/dev/null`;
 	}
 	else {
-		$res = `polygen $grmfile 2>/dev/null`;
+		$res = `polygen $options $grmfile 2>/dev/null`;
 	}
 
 	if ($?) {
diff --git a/debian/changelog b/debian/changelog
index 41a47e57f..f7219d0f5 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -35,7 +35,7 @@ ikiwiki (3.20150330) UNRELEASED; urgency=medium
     if the link text is identical
   * Add a $config{deterministic} option and use it for the docwiki
   * haiku: if deterministic build is requested, return a hard-coded haiku
-  * If deterministic build is requested, return a hard-coded haiku
+  * polygen: if deterministic build is requested, use a well-known random seed
 
  -- Joey Hess <id@joeyh.name>  Tue, 28 Apr 2015 12:24:08 -0400