diff --git a/src/core/copyjob.cpp b/src/core/copyjob.cpp
--- a/src/core/copyjob.cpp
+++ b/src/core/copyjob.cpp
@@ -664,7 +664,10 @@
 {
     struct CopyInfo info;
     info.permissions = entry.numberValue(KIO::UDSEntry::UDS_ACCESS, -1);
-    info.mtime = QDateTime::fromMSecsSinceEpoch(1000 * entry.numberValue(KIO::UDSEntry::UDS_MODIFICATION_TIME, -1), Qt::UTC);
+    const auto timeVal = entry.numberValue(KIO::UDSEntry::UDS_MODIFICATION_TIME, -1);
+    if (timeVal != -1) {
+        info.mtime = QDateTime::fromMSecsSinceEpoch(1000 * timeVal, Qt::UTC);
+    }
     info.ctime = QDateTime::fromMSecsSinceEpoch(1000 * entry.numberValue(KIO::UDSEntry::UDS_CREATION_TIME, -1), Qt::UTC);
     info.size = static_cast<KIO::filesize_t>(entry.numberValue(KIO::UDSEntry::UDS_SIZE, -1));