diff --git a/IkiWiki/Plugin/img.pm b/IkiWiki/Plugin/img.pm
index 740c44f96..79cfba20f 100644
--- a/IkiWiki/Plugin/img.pm
+++ b/IkiWiki/Plugin/img.pm
@@ -174,6 +174,12 @@ sub preprocess (@) {
 		my $r = $im->Read("$format:$srcfile\[$pagenumber]");
 		error sprintf(gettext("failed to read %s: %s"), $file, $r) if $r;
 
+		if ($config{deterministic}) {
+			$im->Set('date:create' => 0);
+			$im->Set('date:modify' => 0);
+			$im->Set('option'      => 'png:exclude-chunk=time');
+		}
+
 		if (! defined $im->Get("width") || ! defined $im->Get("height")) {
 			error sprintf(gettext("failed to get dimensions of %s"), $file);
 		}
diff --git a/t/img.t b/t/img.t
index 20c960500..6049042c2 100755
--- a/t/img.t
+++ b/t/img.t
@@ -155,6 +155,19 @@ ok(! -e "$outpath/666x-really-pdf.jpg");
 like($outhtml, qr/${quot}really-pdf\.png${quot} does not seem to be a valid png file/);
 ok(! -e "$outpath/666x-really-pdf.png");
 
+# resize is deterministic when deterministic=1
+ok(utime(333333333, 333333333, "t/tmp/in/redsquare.png"));
+ok(! system("rm $outpath/10x-redsquare.png"));
+ok(! system(@command, '--set-yaml', 'img_allowed_formats=[JPEG, PNG, svg, pdf]', '--set', 'deterministic=1', "--rebuild"));
+ok(! system("cp $outpath/10x-redsquare.png $outpath/10x-redsquare.png.orig"));
+ok(utime(444444444, 444444444, "t/tmp/in/redsquare.png"));
+ok(! system("rm $outpath/10x-redsquare.png"));
+ok(! system(@command, '--set-yaml', 'img_allowed_formats=[JPEG, PNG, svg, pdf]', '--set', 'deterministic=1', "--rebuild"));
+ok(
+	! system("cmp $outpath/10x-redsquare.png $outpath/10x-redsquare.png.orig"),
+	"resize is deterministic when configured with deterministic=1"
+);
+
 # disable support for uncommon formats and try again
 ok(! system(@command, "--rebuild"));
 ok(! -e "$outpath/10x-bluesquare.png");