diff --git a/extension/src/port/UserInterface/GameType.h b/extension/src/port/UserInterface/GameType.h
index 114d022a..e2f17e12 100644
--- a/extension/src/port/UserInterface/GameType.h
+++ b/extension/src/port/UserInterface/GameType.h
@@ -321,7 +321,7 @@ typedef struct packet_item
     BYTE        count;
 	DWORD		flags;
 	DWORD		anti_flags;
-	long		alSockets[ITEM_SOCKET_SLOT_MAX_NUM];
+	LONG		alSockets[ITEM_SOCKET_SLOT_MAX_NUM]; // PORT: LONG, the 32-bit Win32 long
     TPlayerItemAttribute aAttr[ITEM_ATTRIBUTE_SLOT_MAX_NUM];
 } TItemData;
 
@@ -331,12 +331,15 @@ typedef struct packet_shop_item
     DWORD       price;
     BYTE        count;
 	BYTE		display_pos;
-	long		alSockets[ITEM_SOCKET_SLOT_MAX_NUM];
+	LONG		alSockets[ITEM_SOCKET_SLOT_MAX_NUM]; // PORT: LONG, the 32-bit Win32 long
     TPlayerItemAttribute aAttr[ITEM_ATTRIBUTE_SLOT_MAX_NUM];
 } TShopItemData;
 
 #pragma pack(pop)
 
+// PORT: wire sizes of the 32-bit client (SHOP_SUBHEADER_GC_START/_EX send 40 of these back to back).
+static_assert(sizeof(TShopItemData) == 43, "TShopItemData must match the 40250 wire layout");
+
 inline float GetSqrtDistance(int ix1, int iy1, int ix2, int iy2) // By sqrt
 {
 	float dx, dy;