diff --git a/sfall/Game/combatAI.cpp b/sfall/Game/combatAI.cpp
index 0fd2de4b..355d4459 100644
--- a/sfall/Game/combatAI.cpp
+++ b/sfall/Game/combatAI.cpp
@@ -67,7 +67,7 @@ void __stdcall CombatAI::ai_check_drugs(fo::GameObject* source) {
 
 		long minHP = (hpPercent * fo::func::stat_level(source, fo::Stat::STAT_max_hit_points)) / 100;
 
-		// [FIX] for AI not checking minimum hp properly for using stimpaks (prevents premature fleeing)
+		// [FIX] for AI not checking minimum hp properly for using healing drugs (prevents premature fleeing)
 		if (cap->min_hp > minHP) minHP = cap->min_hp;
 
 		while (fo::func::stat_level(source, fo::Stat::STAT_current_hp) < minHP && source->critter.movePoints >= aiUseItemAPCost) {
@@ -110,7 +110,7 @@ void __stdcall CombatAI::ai_check_drugs(fo::GameObject* source) {
 						while (item->protoId != cap->chem_primary_desire[counter]) if (++counter > 2) break;
 						if (counter <= 2) break; // there is a match
 
-						// [FIX] for AI not taking chem_primary_desire in AI.txt as a preference when using drugs in the inventory
+						// [FIX] for AI not taking chem_primary_desire in AI.txt as a preference list when using drugs in the inventory
 						if (drugUsePerfFixMode == 1) {
 							item = fo::func::inven_find_type(source, fo::ItemType::item_type_drug, &slot);
 							if (!item) {
@@ -121,7 +121,7 @@ void __stdcall CombatAI::ai_check_drugs(fo::GameObject* source) {
 						}
 					} while (counter < 3);
 				} else {
-					// if the durg is equal to the first item of preference, then check the next two (vanilla behavior)
+					// if the drug is equal to the item in the preference list, then check the next (vanilla behavior)
 					while (item->protoId == cap->chem_primary_desire[counter]) if (++counter > 2) break;
 				}
 
@@ -153,7 +153,7 @@ void __stdcall CombatAI::ai_check_drugs(fo::GameObject* source) {
 		}
 	}
 	// search for drugs on the map
-	if (lastItem || (!drugWasUsed /*&& noInvenDrug*/)) {
+	if (lastItem || (!drugWasUsed && noInvenDrug)) {
 		do {
 			if (!lastItem) lastItem = fo::func::ai_search_environ(source, fo::ItemType::item_type_drug);
 			if (!lastItem) lastItem = fo::func::ai_search_environ(source, fo::ItemType::item_type_misc_item);
@@ -191,10 +191,25 @@ static void __declspec(naked) ai_check_drugs_hack() {
 	}
 }
 
+static void __declspec(naked) ai_can_use_drug_hack() {
+	__asm {
+		push ecx; // item
+		call Items::IsHealingItem;
+		pop  ecx;
+		test al, al;
+		retn;
+	}
+}
+
 void CombatAI::init() {
-	// Replace ai_check_drugs_ function
+	// Replace ai_check_drugs_ function for code fixes and checking healing items
 	sf::MakeJump(fo::funcoffs::ai_check_drugs_, ai_check_drugs_hack); // 0x428480
 
+	// Change ai_can_use_drug_ function code to check healing items
+	sf::MakeCall(0x429BDE, ai_can_use_drug_hack, 6);
+	sf::SafeWrite8(0x429BE9, sf::CodeType::JumpNZ);    // jz > jnz
+	sf::SafeWrite8(0x429BF1, sf::CodeType::JumpShort); // jnz > jmp
+
 	drugUsePerfFixMode = sf::IniReader::GetConfigInt("Misc", "AIDrugUsePerfFix", 0);
 	if (drugUsePerfFixMode > 0) sf::dlogr("Applying AI drug use preference fix.", DL_FIX);
 }
diff --git a/sfall/Game/items.cpp b/sfall/Game/items.cpp
index f0b0ab62..a01bd07e 100644
--- a/sfall/Game/items.cpp
+++ b/sfall/Game/items.cpp
@@ -26,16 +26,23 @@ static constexpr int reloadCostAP = 2; // engine default reload AP cost
 
 static std::array<long, 3> healingItemPids = {fo::PID_STIMPAK, fo::PID_SUPER_STIMPAK, fo::PID_HEALING_POWDER};
 
-void Items::SetHealingPID(long index, long pid) {
-	/*if (index >= 0 && index < 3)*/ healingItemPids[index] = pid;
+long Items::GetHealingPID(long index) {
+	return healingItemPids[index];
 }
 
-bool Items::IsHealingItem(fo::GameObject* item) {
-	if (std::find(healingItemPids.cbegin(), healingItemPids.cend(), item->protoId) != healingItemPids.cend()) return true;
+void Items::SetHealingPID(long index, long pid) {
+	healingItemPids[index] = pid;
+}
+
+bool __fastcall Items::IsHealingItem(fo::GameObject* item) {
+	//for each (long pid in healingItemPids) if (pid == item->protoId) return true;
+	if (healingItemPids[0] == item->protoId || healingItemPids[1] == item->protoId || healingItemPids[2] == item->protoId) {
+		return true;
+	}
 
 	fo::Proto* proto;
 	if (fo::GetProto(item->protoId, &proto)) {
-		return ((proto->item.flagsExt & fo::ItemFlags::HealingItem) != 0); // TODO: check asm code
+		return (proto->item.flagsExt & fo::ItemFlags::HealingItem) != 0;
 	}
 	return false;
 }
@@ -54,8 +61,10 @@ bool Items::UseDrugItemFunc(fo::GameObject* source, fo::GameObject* item) {
 
 // Implementation of item_d_take_ engine function with the HOOK_USEOBJON hook
 long Items::item_d_take_drug(fo::GameObject* source, fo::GameObject* item) {
-	if (sf::UseObjOnHook_Invoke(source, item, source) == -1) return -1;
-	return fo::func::item_d_take_drug(source, item);
+	if (sf::UseObjOnHook_Invoke(source, item, source) == -1) { // default handler
+		return fo::func::item_d_take_drug(source, item);
+	}
+	return -1; // cancel the drug use
 }
 
 long Items::item_count(fo::GameObject* who, fo::GameObject* item) {
diff --git a/sfall/Game/items.h b/sfall/Game/items.h
index fc22f677..df25839e 100644
--- a/sfall/Game/items.h
+++ b/sfall/Game/items.h
@@ -13,9 +13,10 @@ class Items {
 public:
 	static void init();
 
+	static long GetHealingPID(long index);
 	static void SetHealingPID(long index, long pid);
 
-	static bool IsHealingItem(fo::GameObject* item);
+	static bool __fastcall IsHealingItem(fo::GameObject* item);
 
 	// True - use failed
 	static bool UseDrugItemFunc(fo::GameObject* source, fo::GameObject* item);
diff --git a/sfall/Modules/BugFixes.cpp b/sfall/Modules/BugFixes.cpp
index f96757a7..d70ced29 100644
--- a/sfall/Modules/BugFixes.cpp
+++ b/sfall/Modules/BugFixes.cpp
@@ -3645,7 +3645,7 @@ void BugFixes::init()
 	//if (drugUsePerfFix > 0) {
 	//	dlog("Applying AI drug use preference fix.", DL_FIX);
 	//	if (drugUsePerfFix == 1) {
-	//		// Fix for AI not taking chem_primary_desire in AI.txt as drug use preference when using drugs in their inventory
+	//		// Fix for AI not taking chem_primary_desire in AI.txt as a preference list when using drugs in the inventory
 	//		MakeCall(0x42869D, ai_check_drugs_hack_break);
 	//		MakeCall(0x4286AB, ai_check_drugs_hack_check, 1);
 	//		MakeCall(0x4286C7, ai_check_drugs_hack_use);
diff --git a/sfall/Modules/FileSystem.cpp b/sfall/Modules/FileSystem.cpp
index cc8808f0..04476801 100644
--- a/sfall/Modules/FileSystem.cpp
+++ b/sfall/Modules/FileSystem.cpp
@@ -712,6 +712,11 @@ void FileSystem::init() {
 	MakeJump(0x47CCE2, FSLoadHook); // LoadGame_
 
 	LoadGameHook::OnGameReset() += FileSystemReset;
+
+	// Fix crash if the filename contains a '%' character (relevant to SFX files)
+	// xfopen_ - remove sprintf_ function calls that do nothing (probably just checking the filename for the '%' formatting char?)
+	BlockCall(0x4DEF12);
+	BlockCall(0x4DEF84);
 }
 
 }
diff --git a/sfall/main.cpp b/sfall/main.cpp
index 68a8145f..a9761adf 100644
--- a/sfall/main.cpp
+++ b/sfall/main.cpp
@@ -118,11 +118,17 @@ static void InitModules() {
 
 	// initialize all modules
 	manager.add<BugFixes>();    // fixes should be applied at the beginning
+	manager.add<FileSystem>();
 	manager.add<Graphics>();
 	manager.add<Input>();
 	manager.add<LoadOrder>();
 	manager.add<LoadGameHook>();
 	manager.add<MainLoopHook>();
+
+	manager.add<Books>();
+	manager.add<Criticals>();
+	manager.add<Elevators>();
+
 	manager.add<Movies>();
 	manager.add<MainMenu>();
 	manager.add<Interface>();
@@ -136,8 +142,7 @@ static void InitModules() {
 	manager.add<Perks>();
 	manager.add<Combat>();
 	manager.add<Skills>();
-	manager.add<FileSystem>();
-	manager.add<Criticals>();
+
 	manager.add<Karma>();
 	manager.add<Tiles>();
 	manager.add<Credits>();
@@ -151,12 +156,10 @@ static void InitModules() {
 	manager.add<Drugs>();       // should be loaded before PartyControl
 	manager.add<PartyControl>();
 	manager.add<BurstMods>();
-	manager.add<Books>();
 	manager.add<Explosions>();
 	manager.add<Message>();
-	manager.add<Elevators>();
 	manager.add<KillCounter>();
-	//
+
 	manager.add<AI>();
 	manager.add<DamageMod>();
 	manager.add<Animations>();