diff --git a/android/app/src/test/java/com/noop/protocol/UnmappedHistoricalLayoutTest.kt b/android/app/src/test/java/com/noop/protocol/UnmappedHistoricalLayoutTest.kt
index adfd90374c..6b6f4311a5 100644
--- a/android/app/src/test/java/com/noop/protocol/UnmappedHistoricalLayoutTest.kt
+++ b/android/app/src/test/java/com/noop/protocol/UnmappedHistoricalLayoutTest.kt
@@ -56,7 +56,11 @@ class UnmappedHistoricalLayoutTest {
     @Test fun unmappedLayoutIsArchivedEvenThoughItsBytesDecodeCleanlyAsV18() {
         // Precondition: read as its true version, this record decodes everything the old screen wanted.
         val asV18 = decodeHistorical(bytes(whoop5V18Hex), DeviceFamily.WHOOP5)!!
-        assertEquals("precondition: these bytes DO decode a unix", 1780916150, asV18["unix"])
+        // #869 widened the decoded `unix` from Int to Long — a u32 with bit 31 set narrowed to a NEGATIVE
+        // Int, which the #547 plausibility gate then dropped, silently losing all history from 2038-01-19
+        // (and today on a future-dated strap). The value here is unchanged; only its type is wider, so the
+        // literal needs the L or assertEquals compares Integer against Long and fails on the box.
+        assertEquals("precondition: these bytes DO decode a unix", 1780916150L, asV18["unix"])
         assertEquals("precondition: these bytes DO decode a heart rate", 102, asV18["heart_rate"])
         assertTrue("precondition: these bytes DO decode a gravity vector", asV18["gravity_x"] is Double)