diff --git a/src/deh_soc.c b/src/deh_soc.c
index 583776ee7..db427b349 100644
--- a/src/deh_soc.c
+++ b/src/deh_soc.c
@@ -2901,7 +2901,9 @@ static boolean GoodDataFileName(const char *s)
 	p = s + strlen(s) - strlen(tail);
 	if (p <= s) return false; // too short
 	if (!fasticmp(p, tail)) return false; // doesn't end in .dat
-	if (fasticmp(s, "gamedata.dat")) return false;
+
+	if (fasticmp(s, "gamedata.dat")) return false; // Don't overwrite default gamedata
+	if (fasticmp(s, "main.dat")) return false; // Don't overwrite default time attack replays
 
 	return true;
 }