diff --git a/crates/pdf/src/tests.rs b/crates/pdf/src/tests.rs
index 6fa4da12a..6ebc0ceac 100644
--- a/crates/pdf/src/tests.rs
+++ b/crates/pdf/src/tests.rs
@@ -37,13 +37,18 @@ fn close(a: Rect, b: Rect, tol: f64) -> bool {
     (a.x0 - b.x0).abs() < tol && (a.y0 - b.y0).abs() < tol && (a.x1 - b.x1).abs() < tol && (a.y1 - b.y1).abs() < tol
 }
 
+/// `d` exported with the default options and imported back: the document a round trip through a PDF
+/// gives.
 fn roundtrip(d: &Document) -> Document {
     let bytes = export(d, &PdfOptions::default()).expect("export");
     import(&bytes).expect("import")
 }
 
+/// `d` exported uncompressed, dated `created: Some(0)` rather than by the clock: two exports of one
+/// document are then the same bytes, where the clock's dates, in whole seconds, differ whenever a
+/// second ticks between them.
 fn uncompressed(d: &Document) -> String {
-    let bytes = export(d, &PdfOptions::uncompressed()).expect("export");
+    let bytes = export(d, &PdfOptions { created: Some(0), ..PdfOptions::uncompressed() }).expect("export");
     String::from_utf8_lossy(&bytes).into_owned()
 }