diff --git a/source/addonStore/models/addon.py b/source/addonStore/models/addon.py
index ffaaecea2e..499e7d6958 100644
--- a/source/addonStore/models/addon.py
+++ b/source/addonStore/models/addon.py
@@ -188,7 +188,8 @@ def isPendingInstall(self) -> bool:
 	def publicationDate(self) -> str | None:
 		if self.submissionTime is None:
 			return None
-		return datetime.strftime(datetime.fromtimestamp(self.submissionTime), "%x")
+		# Convert `self.submissionTime` to seconds.
+		return datetime.strftime(datetime.fromtimestamp(self.submissionTime // 1000), "%x")
 
 
 class _AddonManifestModel(_AddonGUIModel):