diff --git a/Common/Data/Encoding/Shiftjis.h b/Common/Data/Encoding/Shiftjis.h
index 5f77f7665d..7d73ea381a 100644
--- a/Common/Data/Encoding/Shiftjis.h
+++ b/Common/Data/Encoding/Shiftjis.h
@@ -20,6 +20,7 @@ struct ShiftJIS {
 				return INVALID;
 			}
 			// Intentional fall-through.
+			[[fallthrough]];
 		case 0x9:
 		case 0xE:
 			row = ((j & 0x3F) << 1) - 0x01;
diff --git a/Common/UI/Tween.h b/Common/UI/Tween.h
index 229a210b8b..ee20fef026 100644
--- a/Common/UI/Tween.h
+++ b/Common/UI/Tween.h
@@ -65,7 +65,7 @@ template <typename Value>
 class TweenBase: public Tween {
 public:
 	TweenBase(float duration, float (*curve)(float) = [](float f) { return f; })
-		: Tween(duration, curve), from{}, to_{} {
+		: Tween(duration, curve), from_{}, to_{} {
 	}
 	TweenBase(Value from, Value to, float duration, float (*curve)(float) = [](float f) { return f; })
 		: Tween(duration, curve), from_(from), to_(to) {
diff --git a/Core/Dialog/SavedataParam.cpp b/Core/Dialog/SavedataParam.cpp
index 82a7fa532e..26c0a4949e 100644
--- a/Core/Dialog/SavedataParam.cpp
+++ b/Core/Dialog/SavedataParam.cpp
@@ -883,7 +883,7 @@ std::set<std::string> SavedataParam::GetSecureFileNames(const std::string &dirPa
 
 	std::set<std::string> secureFileNames;
 	for (const auto &entry : entries) {
-		char temp[14];
+		char temp[14]{};
 		truncate_cpy(temp, entry.filename);
 		secureFileNames.insert(temp);
 	}
diff --git a/Core/HLE/sceFont.cpp b/Core/HLE/sceFont.cpp
index 6b6049a64b..0715a40dc7 100644
--- a/Core/HLE/sceFont.cpp
+++ b/Core/HLE/sceFont.cpp
@@ -1208,7 +1208,7 @@ static int sceFontFindOptimumFont(u32 libHandle, u32 fontStylePtr, u32 errorCode
 	
 	if (PSP_CoreParameter().compat.flags().Fontltn12Hack && requestedStyle->fontLanguage == 2) {
 		for (size_t j = 0; j < internalFonts.size(); j++) {
-			const auto tempmatchStyle = internalFonts[j]->GetFontStyle();
+			const auto &tempmatchStyle = internalFonts[j]->GetFontStyle();
 			const std::string str(tempmatchStyle.fontFileName);
 			if (str == "ltn12.pgf") {
 				optimumFont = internalFonts[j];
diff --git a/Core/MIPS/IR/IRInst.h b/Core/MIPS/IR/IRInst.h
index 0dbfa67905..4348d527e5 100644
--- a/Core/MIPS/IR/IRInst.h
+++ b/Core/MIPS/IR/IRInst.h
@@ -379,7 +379,7 @@ public:
 		insts_ = w.insts_;
 		return *this;
 	}
-	IRWriter &operator =(IRWriter &&w) {
+	IRWriter &operator =(IRWriter &&w) noexcept {
 		insts_ = std::move(w.insts_);
 		return *this;
 	}
diff --git a/Core/MIPS/IR/IRJit.h b/Core/MIPS/IR/IRJit.h
index c8ef2d5192..063bb40c9c 100644
--- a/Core/MIPS/IR/IRJit.h
+++ b/Core/MIPS/IR/IRJit.h
@@ -51,7 +51,7 @@ public:
 	IRBlock() {}
 	IRBlock(u32 emAddr, u32 origSize, int instOffset, u32 numInstructions)
 		: origAddr_(emAddr), origSize_(origSize), arenaOffset_(instOffset), numIRInstructions_(numInstructions) {}
-	IRBlock(IRBlock &&b) {
+	IRBlock(IRBlock &&b) noexcept {
 		arenaOffset_ = b.arenaOffset_;
 		hash_ = b.hash_;
 		origAddr_ = b.origAddr_;
diff --git a/Core/MIPS/MIPS.cpp b/Core/MIPS/MIPS.cpp
index a5e522ce6b..3993962999 100644
--- a/Core/MIPS/MIPS.cpp
+++ b/Core/MIPS/MIPS.cpp
@@ -207,6 +207,8 @@ void MIPSState::Init() {
 	nextPC = 0;
 	downcount = 0;
 
+	memset(vcmpResult, 0, sizeof(vcmpResult));
+
 	std::lock_guard<std::recursive_mutex> guard(MIPSComp::jitLock);
 	if (PSP_CoreParameter().cpuCore == CPUCore::JIT || PSP_CoreParameter().cpuCore == CPUCore::JIT_IR) {
 		MIPSComp::jit = MIPSComp::CreateNativeJit(this, PSP_CoreParameter().cpuCore == CPUCore::JIT_IR);
diff --git a/Core/MIPS/MIPSIntVFPU.cpp b/Core/MIPS/MIPSIntVFPU.cpp
index c5d712beff..f0ae68a799 100644
--- a/Core/MIPS/MIPSIntVFPU.cpp
+++ b/Core/MIPS/MIPSIntVFPU.cpp
@@ -961,9 +961,11 @@ namespace MIPSInt
 			case V_Triple:
 				sz = V_Pair;
 				// Intentional fallthrough.
+				[[fallthrough]];
 			case V_Pair:
 				oz = V_Quad;
 				// Intentional fallthrough.
+				[[fallthrough]];
 			case V_Single:
 				for (int i = 0; i < GetNumVectorElements(sz); i++) {
 					u32 value = s[i];
@@ -985,9 +987,11 @@ namespace MIPSInt
 			case V_Triple:
 				sz = V_Pair;
 				// Intentional fallthrough.
+				[[fallthrough]];
 			case V_Pair:
 				oz = V_Quad;
 				// Intentional fallthrough.
+				[[fallthrough]];
 			case V_Single:
 				for (int i = 0; i < GetNumVectorElements(sz); i++) {
 					u32 value = s[i];
diff --git a/Core/Util/BlockAllocator.cpp b/Core/Util/BlockAllocator.cpp
index 72907d7aea..e580c2eb7a 100644
--- a/Core/Util/BlockAllocator.cpp
+++ b/Core/Util/BlockAllocator.cpp
@@ -27,10 +27,6 @@
 
 // Slow freaking thing but works (eventually) :)
 
-BlockAllocator::BlockAllocator(int grain) : bottom_(NULL), top_(NULL), grain_(grain)
-{
-}
-
 BlockAllocator::~BlockAllocator()
 {
 	Shutdown();
diff --git a/Core/Util/BlockAllocator.h b/Core/Util/BlockAllocator.h
index 91e9642462..51a4038ca1 100644
--- a/Core/Util/BlockAllocator.h
+++ b/Core/Util/BlockAllocator.h
@@ -24,7 +24,7 @@ class PointerWrap;
 class BlockAllocator
 {
 public:
-	BlockAllocator(int grain = 16);  // 16 byte granularity by default.
+	BlockAllocator(int grain = 16) : grain_(grain) {}  // 16 byte granularity by default.
 	~BlockAllocator();
 
 	void Init(u32 _rangeStart, u32 _rangeSize, bool suballoc);
@@ -59,8 +59,7 @@ public:
 private:
 	void CheckBlocks() const;
 
-	struct Block
-	{
+	struct Block {
 		Block(u32 _start, u32 _size, bool _taken, Block *_prev, Block *_next);
 		void SetAllocated(const char *_tag, bool suballoc);
 		void DoState(PointerWrap &p);
@@ -72,13 +71,13 @@ private:
 		Block *next;
 	};
 
-	Block *bottom_;
-	Block *top_;
-	u32 rangeStart_;
-	u32 rangeSize_;
+	Block *bottom_ = nullptr;
+	Block *top_ = nullptr;
+	u32 rangeStart_ = 0;
+	u32 rangeSize_ = 0;
 
 	u32 grain_;
-	bool suballoc_;
+	bool suballoc_ = false;
 
 	void MergeFreeBlocks(Block *fromBlock);
 	Block *GetBlockFromAddress(u32 addr);
diff --git a/Core/Util/DisArm64.cpp b/Core/Util/DisArm64.cpp
index aa49af09cd..2414eec409 100644
--- a/Core/Util/DisArm64.cpp
+++ b/Core/Util/DisArm64.cpp
@@ -418,7 +418,7 @@ static void DataProcessingRegister(uint32_t w, uint64_t addr, Instruction *instr
 		int opcode2 = (w >> 16) & 0x1F;
 		int opcode = (w >> 10) & 0x3F;
 		// Data-processing (1 source)
-		const char *opname[8] = { "rbit", "rev16", "rev32", "(unk)", "clz", "cls" };
+		const char *opname[64] = { "rbit", "rev16", "rev32", "(unk)", "clz", "cls" };
 		const char *op = opcode2 >= 8 ? "unk" : opname[opcode];
 		snprintf(instr->text, sizeof(instr->text), "%s %c%d, %c%d", op, r, Rd, r, Rn);
 	} else if (((w >> 21) & 0x2FF) == 0x0D6) {
@@ -749,7 +749,7 @@ static void FPandASIMD1(uint32_t w, uint64_t addr, Instruction *instr) {
 				int dst_index = imm5 >> (size + 1);
 				int src_index = imm4 >> size;
 				int op = (w >> 29) & 1;
-				char s;
+				char s = '_';
 				switch (size) {
 				case 0x00: s = 'b'; break;
 				case 0x01: s = 'h'; break;
diff --git a/Core/Util/GameDB.h b/Core/Util/GameDB.h
index 5d211da724..babf63e244 100644
--- a/Core/Util/GameDB.h
+++ b/Core/Util/GameDB.h
@@ -12,8 +12,8 @@ class VFSInterface;
 struct GameDBInfo {
 	std::string title;
 	std::string foreignTitle;
-	uint32_t crc;
-	uint64_t size;
+	uint32_t crc = 0;
+	uint64_t size = 0;
 };
 
 class GameDB {
diff --git a/ext/riscv-disas.cpp b/ext/riscv-disas.cpp
index 816c985cca..a4868ae50d 100644
--- a/ext/riscv-disas.cpp
+++ b/ext/riscv-disas.cpp
@@ -2233,7 +2233,7 @@ static void decode_inst_operands(rv_decode *dec)
 
 static void decode_inst_decompress(rv_decode *dec, rv_isa isa)
 {
-    int decomp_op;
+    int decomp_op = 0;
     switch (isa) {
     case rv32: decomp_op = opcode_data[dec->op].decomp_rv32; break;
     case rv64: decomp_op = opcode_data[dec->op].decomp_rv64; break;