diff --git a/src/Player.cc b/src/Player.cc
index 10b0716a..ac4f4d11 100644
--- a/src/Player.cc
+++ b/src/Player.cc
@@ -540,7 +540,7 @@ PlayerBankItem::PlayerBankItem()
 
 PlayerBankItem::PlayerBankItem(const PlayerInventoryItem& src)
   : data(src.data),
-    amount(combine_item_to_max.count(this->data.primary_identifier()) ? this->data.data1[5] : 1),
+    amount(stack_size_for_item(this->data)),
     show_flags(1) { }
 
 
@@ -569,9 +569,8 @@ void SavedPlayerDataBB::add_item(const PlayerInventoryItem& item) {
   }
 
   // Handle combinable items
-  try {
-    uint32_t combine_max = combine_item_to_max.at(pid);
-
+  size_t combine_max = stack_size_for_item(item.data);
+  if (combine_max > 1) {
     // Get the item index if there's already a stack of the same item in the
     // player's inventory
     size_t y;
@@ -589,7 +588,7 @@ void SavedPlayerDataBB::add_item(const PlayerInventoryItem& item) {
       }
       return;
     }
-  } catch (const out_of_range&) { }
+  }
 
   // If we get here, then it's not meseta and not a combine item, so it needs to
   // go into an empty inventory slot
@@ -611,9 +610,8 @@ void PlayerBank::add_item(const PlayerBankItem& item) {
     return;
   }
 
-  try {
-    uint32_t combine_max = combine_item_to_max.at(pid);
-
+  size_t combine_max = stack_size_for_item(item.data);
+  if (combine_max > 1) {
     size_t y;
     for (y = 0; y < this->num_items; y++) {
       if (this->items[y].data.primary_identifier() == item.data.primary_identifier()) {
@@ -629,7 +627,7 @@ void PlayerBank::add_item(const PlayerBankItem& item) {
       this->items[y].amount = this->items[y].data.data1[5];
       return;
     }
-  } catch (const out_of_range&) { }
+  }
 
   if (this->num_items >= 200) {
     throw runtime_error("bank is full");
@@ -663,8 +661,8 @@ PlayerInventoryItem SavedPlayerDataBB::remove_item(
   // then create a new item and reduce the amount of the existing stack. Note
   // that passing amount == 0 means to remove the entire stack, so this only
   // applies if amount is nonzero.
-  if (amount && (amount < inventory_item.data.data1[5]) &&
-      combine_item_to_max.count(inventory_item.data.primary_identifier())) {
+  if (amount && (stack_size_for_item(inventory_item.data) > 1) &&
+      (amount < inventory_item.data.data1[5])) {
     ret = inventory_item;
     ret.data.data1[5] = amount;
     ret.data.id = 0xFFFFFFFF;
@@ -700,8 +698,8 @@ PlayerBankItem PlayerBank::remove_item(uint32_t item_id, uint32_t amount) {
   size_t index = this->find_item(item_id);
   auto& bank_item = this->items[index];
 
-  if (amount && (amount < bank_item.data.data1[5]) &&
-      combine_item_to_max.count(bank_item.data.primary_identifier())) {
+  if (amount && (stack_size_for_item(bank_item.data) > 1) &&
+      (amount < bank_item.data.data1[5])) {
     ret = bank_item;
     ret.data.data1[5] = amount;
     ret.amount = amount;
diff --git a/src/RareItemSet.hh b/src/RareItemSet.hh
index 62ca43c2..a779cb6c 100644
--- a/src/RareItemSet.hh
+++ b/src/RareItemSet.hh
@@ -10,6 +10,10 @@ struct RareItemDrop {
 } __attribute__((packed));
 
 struct RareItemSet {
+  // TODO: It looks like this structure can actually vary. We see the offsets
+  // 0194 and 01B2 in the unused section, along with the value 1E (number of box
+  // rares). In PSOGC, these all appear to be the same size/format, but that's
+  // probably not strictly required to be the case.
   // 0x280 in size; describes one difficulty, section ID, and episode
   RareItemDrop rares[0x65];     // 0000 - 0194 in file
   uint8_t box_areas[0x1E];      // 0194 - 01B2 in file
diff --git a/src/StaticGameData.cc b/src/StaticGameData.cc
index 5cce8ed2..c01a76a7 100644
--- a/src/StaticGameData.cc
+++ b/src/StaticGameData.cc
@@ -253,24 +253,25 @@ uint8_t npc_for_name(const u16string& name) {
 
 
 
-const unordered_map<uint32_t, uint32_t> combine_item_to_max({
-  {0x030000, 10},
-  {0x030001, 10},
-  {0x030002, 10},
-  {0x030100, 10},
-  {0x030101, 10},
-  {0x030102, 10},
-  {0x030300, 10},
-  {0x030400, 10},
-  {0x030500, 10},
-  {0x030600, 10},
-  {0x030601, 10},
-  {0x030700, 10},
-  {0x030800, 10},
-  {0x031000, 99},
-  {0x031001, 99},
-  {0x031002, 99},
-});
+size_t stack_size_for_item(uint8_t data0, uint8_t data1) {
+  if (data0 == 4) {
+    return 999999;
+  }
+  if (data0 == 3) {
+    if ((data1 < 9) && (data1 != 2)) {
+      return 10;
+    } else if (data1 == 0x10) {
+      return 99;
+    }
+  }
+  return 1;
+}
+
+size_t stack_size_for_item(const ItemData& item) {
+  return stack_size_for_item(item.data1[0], item.data1[1]);
+}
+
+
 
 const unordered_map<uint8_t, const char*> name_for_weapon_special({
   {0x00, nullptr},
@@ -1592,7 +1593,7 @@ string name_for_item(const ItemData& item, bool include_color_codes) {
 
   // For tools, add the amount (if applicable)
   } else if (item.data1[0] == 0x03) {
-    if (combine_item_to_max.count(primary_identifier)) {
+    if (stack_size_for_item(item) > 1) {
       ret_tokens.emplace_back(string_printf("x%hhu", item.data1[5]));
     }
   }
diff --git a/src/StaticGameData.hh b/src/StaticGameData.hh
index 1d0facd6..73927905 100644
--- a/src/StaticGameData.hh
+++ b/src/StaticGameData.hh
@@ -8,7 +8,9 @@
 
 
 
-extern const std::unordered_map<uint32_t, uint32_t> combine_item_to_max;
+size_t stack_size_for_item(uint8_t data0, uint8_t data1);
+size_t stack_size_for_item(const ItemData& item);
+
 extern const std::unordered_map<uint8_t, const char*> name_for_weapon_special;
 extern const std::unordered_map<uint8_t, const char*> name_for_s_rank_special;
 extern const std::unordered_map<uint32_t, const char*> name_for_primary_identifier;