diff --git a/PKHeX/Legality/Core.cs b/PKHeX/Legality/Core.cs
index 86f384ac6..c7c9865ad 100644
--- a/PKHeX/Legality/Core.cs
+++ b/PKHeX/Legality/Core.cs
@@ -331,7 +331,7 @@ internal static EncounterTrade getValidIngameTrade(PKM pkm, bool gen1Encounter =
 
             int lvl = (pkm.HasOriginalMetLocation) ? pkm.Met_Level : getMaxLevelGeneration(pkm);
             if (lvl <= 0)
-                return lvl;
+                return null;
             // Get valid pre-evolutions
             IEnumerable<DexLevel> p = getValidPreEvolutions(pkm);