diff --git a/Core/Debugger/WebSocket/HLESubscriber.cpp b/Core/Debugger/WebSocket/HLESubscriber.cpp
index f03f114206..b749fb3029 100644
--- a/Core/Debugger/WebSocket/HLESubscriber.cpp
+++ b/Core/Debugger/WebSocket/HLESubscriber.cpp
@@ -247,12 +247,16 @@ void WebSocketHLEFuncAdd(DebuggerRequest &req) {
 	u32 addr;
 	if (!req.ParamU32("address", &addr))
 		return;
+
 	u32 size = -1;
 	if (!req.ParamU32("size", &size, false, DebuggerParamType::OPTIONAL))
 		return;
 	if (size == 0)
 		size = -1;
 
+	addr &= ~0x3; // Align.
+	size = (size + 3) & ~0x3; // Align.
+
 	std::string name;
 	if (!req.ParamString("name", &name, DebuggerParamType::OPTIONAL))
 		return;
@@ -260,7 +264,7 @@ void WebSocketHLEFuncAdd(DebuggerRequest &req) {
 		name = StringFromFormat("z_un_%08x", addr);
 
 	u32 prevBegin = g_symbolMap->GetFunctionStart(addr);
-	u32 endBegin = size == -1 ? prevBegin : g_symbolMap->GetFunctionStart(addr + size - 1);
+	u32 endBegin = size == -1 ? prevBegin : g_symbolMap->GetFunctionStart(addr + size - 4);
 	if (prevBegin == addr) {
 		return req.Fail("Function already exists at 'address'");
 	} else if (endBegin != prevBegin) {
@@ -275,7 +279,7 @@ void WebSocketHLEFuncAdd(DebuggerRequest &req) {
 			size = prevSize - newPrevSize;
 
 		// Make sure we register the new length for replacements too.
-		MIPSAnalyst::ForgetFunctions(prevBegin, prevBegin + newPrevSize - 1);
+		MIPSAnalyst::ForgetFunctions(prevBegin, prevBegin + newPrevSize);
 		g_symbolMap->SetFunctionSize(prevBegin, newPrevSize);
 		MIPSAnalyst::RegisterFunction(prevBegin, newPrevSize, prevName.c_str());
 	} else {
@@ -285,7 +289,7 @@ void WebSocketHLEFuncAdd(DebuggerRequest &req) {
 	}
 
 	// To ensure we restore replacements.
-	MIPSAnalyst::ForgetFunctions(addr, addr + size - 1);
+	MIPSAnalyst::ForgetFunctions(addr, addr + size);
 	g_symbolMap->AddFunction(name.c_str(), addr, size);
 	g_symbolMap->SortSymbols();
 	MIPSAnalyst::RegisterFunction(addr, size, name.c_str());
@@ -326,6 +330,8 @@ void WebSocketHLEFuncRemove(DebuggerRequest &req) {
 	if (!req.ParamU32("address", &addr))
 		return;
 
+	addr &= ~0x3; // Align.
+
 	u32 funcBegin = g_symbolMap->GetFunctionStart(addr);
 	if (funcBegin == -1)
 		return req.Fail("No function found at 'address'");
@@ -337,10 +343,10 @@ void WebSocketHLEFuncRemove(DebuggerRequest &req) {
 		std::string prevName = g_symbolMap->GetLabelString(prevBegin);
 		u32 expandedSize = g_symbolMap->GetFunctionSize(prevBegin) + funcSize;
 		g_symbolMap->SetFunctionSize(prevBegin, expandedSize);
-		MIPSAnalyst::ForgetFunctions(prevBegin, prevBegin + expandedSize - 1);
+		MIPSAnalyst::ForgetFunctions(prevBegin, prevBegin + expandedSize);
 		MIPSAnalyst::RegisterFunction(prevBegin, expandedSize, prevName.c_str());
 	} else {
-		MIPSAnalyst::ForgetFunctions(funcBegin, funcBegin + funcSize - 1);
+		MIPSAnalyst::ForgetFunctions(funcBegin, funcBegin + funcSize);
 	}
 
 	g_symbolMap->RemoveFunction(funcBegin, true);
@@ -378,7 +384,7 @@ static u32 RemoveFuncSymbolsInRange(u32 addr, u32 size) {
 	}
 
 	if (counter) {
-		MIPSAnalyst::ForgetFunctions(addr, addr + size - 1);
+		MIPSAnalyst::ForgetFunctions(addr, addr + size);
 
 		// The following was copied from hle.func.remove:
 		g_symbolMap->SortSymbols();
@@ -413,10 +419,14 @@ void WebSocketHLEFuncRemoveRange(DebuggerRequest &req) {
 	u32 addr;
 	if (!req.ParamU32("address", &addr))
 		return;
+
 	u32 size;
 	if (!req.ParamU32("size", &size))
 		return;
 
+	addr &= ~0x3; // Align.
+	size = (size + 3) & ~0x3; // Align.
+
 	if (!Memory::IsValidRange(addr, size))
 		return req.Fail("Address or size outside valid memory");
 
@@ -449,6 +459,8 @@ void WebSocketHLEFuncRename(DebuggerRequest &req) {
 	if (!req.ParamString("name", &name))
 		return;
 
+	addr &= ~0x3; // Align.
+
 	u32 funcBegin = g_symbolMap->GetFunctionStart(addr);
 	if (funcBegin == -1)
 		return req.Fail("No function found at 'address'");
@@ -456,7 +468,7 @@ void WebSocketHLEFuncRename(DebuggerRequest &req) {
 
 	g_symbolMap->SetLabelName(name.c_str(), funcBegin);
 	// To ensure we reapply replacements (in case we check name there.)
-	MIPSAnalyst::ForgetFunctions(funcBegin, funcBegin + funcSize - 1);
+	MIPSAnalyst::ForgetFunctions(funcBegin, funcBegin + funcSize);
 	MIPSAnalyst::RegisterFunction(funcBegin, funcSize, name.c_str());
 	MIPSAnalyst::UpdateHashMap();
 	MIPSAnalyst::ApplyHashMap();
@@ -487,10 +499,15 @@ void WebSocketHLEFuncScan(DebuggerRequest &req) {
 	u32 addr;
 	if (!req.ParamU32("address", &addr))
 		return;
+
+
 	u32 size;
 	if (!req.ParamU32("size", &size))
 		return;
 
+	addr &= ~0x3; // Align.
+	size = (size + 3) & ~0x3; // Align.
+
 	bool remove = false;
 	if (!req.ParamBool("remove", &remove, DebuggerParamType::OPTIONAL))
 		return;
@@ -502,7 +519,7 @@ void WebSocketHLEFuncScan(DebuggerRequest &req) {
 		RemoveFuncSymbolsInRange(addr, size);
 	}
 
-	bool insertSymbols = MIPSAnalyst::ScanForFunctions(addr, addr + size - 1, true);
+	bool insertSymbols = MIPSAnalyst::ScanForFunctions(addr, addr + size, true);
 	MIPSAnalyst::FinalizeScan(insertSymbols);
 
 	req.Respond();
diff --git a/Core/HLE/sceKernelModule.cpp b/Core/HLE/sceKernelModule.cpp
index 2be7c21793..01c3b57cb2 100644
--- a/Core/HLE/sceKernelModule.cpp
+++ b/Core/HLE/sceKernelModule.cpp
@@ -1352,11 +1352,11 @@ static PSPModule *__KernelLoadELFFromPtr(const u8 *ptr, size_t elfSize, u32 load
 			if (Memory::IsValid4AlignedRange(scanStart, scanEnd - scanStart)) {
 				// Skip the exports and imports sections, they're not code.
 				if (scanEnd >= std::min(modinfo->libent, modinfo->libstub)) {
-					insertSymbols = MIPSAnalyst::ScanForFunctions(scanStart, std::min(modinfo->libent, modinfo->libstub) - 4, insertSymbols);
+					insertSymbols = MIPSAnalyst::ScanForFunctions(scanStart, std::min(modinfo->libent, modinfo->libstub), insertSymbols);
 					scanStart = std::min(modinfo->libentend, modinfo->libstubend);
 				}
 				if (scanEnd >= std::max(modinfo->libent, modinfo->libstub)) {
-					insertSymbols = MIPSAnalyst::ScanForFunctions(scanStart, std::max(modinfo->libent, modinfo->libstub) - 4, insertSymbols);
+					insertSymbols = MIPSAnalyst::ScanForFunctions(scanStart, std::max(modinfo->libent, modinfo->libstub), insertSymbols);
 					scanStart = std::max(modinfo->libentend, modinfo->libstubend);
 				}
 				insertSymbols = MIPSAnalyst::ScanForFunctions(scanStart, scanEnd, insertSymbols);
diff --git a/Core/MIPS/MIPSAnalyst.cpp b/Core/MIPS/MIPSAnalyst.cpp
index c7fed20c6b..516a3bb6a8 100644
--- a/Core/MIPS/MIPSAnalyst.cpp
+++ b/Core/MIPS/MIPSAnalyst.cpp
@@ -1001,8 +1001,10 @@ skip:
 		return furthestJumpbackAddr;
 	}
 
+	// endAddr is exclusive.
 	bool ScanForFunctions(u32 startAddr, u32 endAddr, bool insertSymbols) {
 		_assert_((startAddr & 3) == 0);
+		_assert_((endAddr & 3) == 0);
 
 		std::lock_guard<std::recursive_mutex> guard(functions_lock);
 
@@ -1017,7 +1019,7 @@ skip:
 		bool decreasedSp = false;
 
 		u32 addr;
-		for (addr = startAddr; addr <= endAddr; addr += 4) {
+		for (addr = startAddr; addr < endAddr; addr += 4) {
 			MIPSOpcode op = Memory::Read_Instruction(addr, true);
 			u32 target = GetBranchTargetNoRA(addr, op);
 			if (target != INVALIDTARGET) {
@@ -1141,7 +1143,7 @@ skip:
 			}
 		}
 
-		if (addr <= endAddr) {
+		if (addr < endAddr) {
 			currentFunction.end = addr + 4;
 			new_functions.push_back(currentFunction);
 		}
@@ -1186,6 +1188,7 @@ skip:
 
 	void RegisterFunction(u32 startAddr, u32 size, const char *name) {
 		_assert_((startAddr & 3) == 0);
+		_assert_((size & 3) == 0);
 
 		std::lock_guard<std::recursive_mutex> guard(functions_lock);
 
@@ -1219,19 +1222,23 @@ skip:
 		HashFunctions();
 	}
 
+	// endAddr is exclusive.
 	void ForgetFunctions(u32 startAddr, u32 endAddr) {
 		std::lock_guard<std::recursive_mutex> guard(functions_lock);
 
+		_assert_((startAddr & 3) == 0);
+		_assert_((endAddr & 3) == 0);
+
 		// It makes sense to forget functions as modules are unloaded but it breaks
 		// the easy way of saving a hashmap by unloading and loading a game. I added
 		// an alternative way.
 
-		// Most of the time, functions from the same module will be contiguous in functions.
+		// Most of the time, functions from the same module will be contiguous in the vector, in address order.
 		FunctionsVector::iterator prevMatch = functions.end();
 		size_t originalSize = functions.size();
 		for (auto iter = functions.begin(); iter != functions.end(); ++iter) {
 			const bool hadPrevMatch = prevMatch != functions.end();
-			const bool match = iter->start >= startAddr && iter->start <= endAddr;
+			const bool match = iter->start >= startAddr && iter->start < endAddr;
 
 			if (!hadPrevMatch && match) {
 				// Entering a range.
diff --git a/Windows/Debugger/EditSymbolsWindow.cpp b/Windows/Debugger/EditSymbolsWindow.cpp
index a50144b67b..e9e44408e7 100644
--- a/Windows/Debugger/EditSymbolsWindow.cpp
+++ b/Windows/Debugger/EditSymbolsWindow.cpp
@@ -165,7 +165,7 @@ void EditSymbolsWindow::Remove() {
 	}
 
 	if (counter) {
-		MIPSAnalyst::ForgetFunctions(address_, address_ + size_ - 1);
+		MIPSAnalyst::ForgetFunctions(address_, address_ + size_);
 
 		// The following was copied from hle.func.remove:
 		g_symbolMap->SortSymbols();