diff --git a/Common/ArmEmitter.cpp b/Common/ArmEmitter.cpp
index 9ba1a59d29..2d55b8dffa 100644
--- a/Common/ArmEmitter.cpp
+++ b/Common/ArmEmitter.cpp
@@ -748,7 +748,7 @@ void ARMXEmitter::B(ARMReg src)
 	Write32(condition | 0x012FFF10 | src);
 }
 
-bool ARMXEmitter::BLInRange(const void *fnptr) {
+bool ARMXEmitter::BLInRange(const void *fnptr) const {
 	ptrdiff_t distance = (intptr_t)fnptr - (intptr_t(code) + 8);
 	if (distance <= -0x2000000 || distance > 0x2000000)
 		return false;
diff --git a/Common/ArmEmitter.h b/Common/ArmEmitter.h
index 206338e445..d571742486 100644
--- a/Common/ArmEmitter.h
+++ b/Common/ArmEmitter.h
@@ -143,7 +143,7 @@ private:
 	u8 IndexOrShift;
 	ShiftType Shift;
 public:
-	OpType GetType()
+	OpType GetType() const
 	{
 		return Type;
 	}
@@ -240,35 +240,35 @@ public:
 		_assert_msg_(JIT, Type == TYPE_RSR, "RSR must be RSR Of Course");
 		return (IndexOrShift << 8) | (Shift << 5) | 0x10 | Value;
 	}
-	u32 Rm()
+	u32 Rm() const
 	{
 		_assert_msg_(JIT, Type == TYPE_REG, "Rm must be with Reg");
 		return Value;
 	}
 
-	u32 Imm5()
+	u32 Imm5() const
 	{
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm5 not IMM value");
 		return ((Value & 0x0000001F) << 7);
 	}
-	u32 Imm8()
+	u32 Imm8() const
 	{
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm8Rot not IMM value");
 		return Value & 0xFF;
 	}
-	u32 Imm8Rot() // IMM8 with Rotation
+	u32 Imm8Rot() const // IMM8 with Rotation
 	{
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm8Rot not IMM value");
 		_assert_msg_(JIT, (Rotation & 0xE1) != 0, "Invalid Operand2: immediate rotation %u", Rotation);
 		return (1 << 25) | (Rotation << 7) | (Value & 0x000000FF);
 	}
-	u32 Imm12()
+	u32 Imm12() const
 	{
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm12 not IMM");
 		return (Value & 0x00000FFF);
 	}
 
-	u32 Imm12Mod()
+	u32 Imm12Mod() const
 	{
 		// This is an IMM12 with the top four bits being rotation and the
 		// bottom eight being an IMM. This is for instructions that need to
@@ -278,32 +278,32 @@ public:
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm12Mod not IMM");
 		return ((Rotation & 0xF) << 8) | (Value & 0xFF);
 	}
-	u32 Imm16()
+	u32 Imm16() const
 	{
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm16 not IMM");
 		return ( (Value & 0xF000) << 4) | (Value & 0x0FFF);
 	}
-	u32 Imm16Low()
+	u32 Imm16Low() const
 	{
 		return Imm16();
 	}
-	u32 Imm16High() // Returns high 16bits
+	u32 Imm16High() const // Returns high 16bits
 	{
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm16 not IMM");
 		return ( ((Value >> 16) & 0xF000) << 4) | ((Value >> 16) & 0x0FFF);
 	}
-	u32 Imm24()
+	u32 Imm24() const
 	{
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm16 not IMM");
 		return (Value & 0x0FFFFFFF);
 	}
 	// NEON and ASIMD specific
-	u32 Imm8ASIMD()
+	u32 Imm8ASIMD() const
 	{
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm8ASIMD not IMM");
 		return  ((Value & 0x80) << 17) | ((Value & 0x70) << 12) | (Value & 0xF);
 	}
-	u32 Imm8VFP()
+	u32 Imm8VFP() const
 	{
 		_assert_msg_(JIT, (Type == TYPE_IMM), "Imm8VFP not IMM");
 		return ((Value & 0xF0) << 12) | (Value & 0xF);
@@ -511,7 +511,7 @@ public:
 	void B (ARMReg src);
 	void BL(const void *fnptr);
 	void BL(ARMReg src);
-	bool BLInRange(const void *fnptr);
+	bool BLInRange(const void *fnptr) const;
 
 	void PUSH(const int num, ...);
 	void POP(const int num, ...);
diff --git a/Common/MemoryUtil.h b/Common/MemoryUtil.h
index 68a40dbf1c..3f6812434c 100644
--- a/Common/MemoryUtil.h
+++ b/Common/MemoryUtil.h
@@ -75,7 +75,7 @@ public:
 		return buf_;
 	}
 
-	size_t size() {
+	size_t size() const {
 		return size_;
 	}
 
diff --git a/Common/Timer.cpp b/Common/Timer.cpp
index 89f10db9e3..b45a7d4c34 100644
--- a/Common/Timer.cpp
+++ b/Common/Timer.cpp
@@ -93,7 +93,7 @@ void Timer::Update()
 // -------------------------------------
 
 // Get the number of milliseconds since the last Update()
-u64 Timer::GetTimeDifference()
+u64 Timer::GetTimeDifference() const
 {
 	return GetTimeMs() - m_LastTime;
 }
@@ -112,7 +112,7 @@ void Timer::WindBackStartingTime(u64 WindBack)
 }
 
 // Get the time elapsed since the Start()
-u64 Timer::GetTimeElapsed()
+u64 Timer::GetTimeElapsed() const
 {
 	// If we have not started yet, return 1 (because then I don't
 	// have to change the FPS calculation in CoreRerecording.cpp .
diff --git a/Common/Timer.h b/Common/Timer.h
index 5ccfb69aa5..dbe19f5469 100644
--- a/Common/Timer.h
+++ b/Common/Timer.h
@@ -33,7 +33,7 @@ public:
 	void Update();
 
 	// The time difference is always returned in milliseconds, regardless of alternative internal representation
-	u64 GetTimeDifference();
+	u64 GetTimeDifference() const;
 	void AddTimeDifference();
 	void WindBackStartingTime(u64 WindBack);
 
@@ -45,7 +45,7 @@ public:
 
   static void GetTimeFormatted(char formattedTime[13]);
 	std::string GetTimeElapsedFormatted() const;
-	u64 GetTimeElapsed();
+	u64 GetTimeElapsed() const;
 
 	static u32 GetTimeMs();
 
diff --git a/Core/FileSystems/VirtualDiscFileSystem.h b/Core/FileSystems/VirtualDiscFileSystem.h
index f219f223a7..aab5f10fff 100644
--- a/Core/FileSystems/VirtualDiscFileSystem.h
+++ b/Core/FileSystems/VirtualDiscFileSystem.h
@@ -84,7 +84,7 @@ private:
 		ReadFunc Read;
 		CloseFunc Close;
 
-		bool IsValid() { return library != NULL; }
+		bool IsValid() const { return library != NULL; }
 	};
 
 	struct HandlerFileHandle {
diff --git a/Core/HLE/scePsmf.cpp b/Core/HLE/scePsmf.cpp
index c180bfc50b..ba1b3b6b6c 100644
--- a/Core/HLE/scePsmf.cpp
+++ b/Core/HLE/scePsmf.cpp
@@ -170,7 +170,7 @@ public:
 	void setStreamNum(int num);
 	bool setStreamWithType(int type, int channel);
 
-	int FindEPWithTimestamp(int pts);
+	int FindEPWithTimestamp(int pts) const;
 
 	u32 magic;
 	u32 version;
@@ -548,7 +548,7 @@ bool Psmf::setStreamWithType(int type, int channel) {
 	return false;
 }
 
-int Psmf::FindEPWithTimestamp(int pts) {
+int Psmf::FindEPWithTimestamp(int pts) const {
 	int best = -1;
 	int bestPts = 0;
 
diff --git a/Core/MIPS/PPC/PpcRegCache.cpp b/Core/MIPS/PPC/PpcRegCache.cpp
index 53a0711f68..b44e463cf3 100644
--- a/Core/MIPS/PPC/PpcRegCache.cpp
+++ b/Core/MIPS/PPC/PpcRegCache.cpp
@@ -41,7 +41,7 @@ void PpcRegCache::Start(MIPSAnalyst::AnalysisResults &stats) {
 	}
 }
 
-const PPCReg *PpcRegCache::GetMIPSAllocationOrder(int &count) {
+const PPCReg *PpcRegCache::GetMIPSAllocationOrder(int &count) const {
 	// Note that R0 is reserved as scratch for now.
 	// R1 could be used as it's only used for scratch outside "regalloc space" now.
 	// R12 is also potentially usable.
diff --git a/Core/MIPS/PPC/PpcRegCache.h b/Core/MIPS/PPC/PpcRegCache.h
index c74b98b1e0..5f982bbe7f 100644
--- a/Core/MIPS/PPC/PpcRegCache.h
+++ b/Core/MIPS/PPC/PpcRegCache.h
@@ -139,8 +139,8 @@ public:
 	int GetMipsRegOffset(MIPSReg r);
 
 private:
-	const PPCReg *GetMIPSAllocationOrder(int &count);
-		
+	const PPCReg *GetMIPSAllocationOrder(int &count) const;
+
 	MIPSState *mips_;
 	MIPSComp::PpcJitOptions *options_;
 	PPCXEmitter *emit_;
diff --git a/Core/MIPS/PPC/PpcRegCacheVPU.cpp b/Core/MIPS/PPC/PpcRegCacheVPU.cpp
index 905ce47db4..59faa11a62 100644
--- a/Core/MIPS/PPC/PpcRegCacheVPU.cpp
+++ b/Core/MIPS/PPC/PpcRegCacheVPU.cpp
@@ -41,7 +41,7 @@ void PpcRegCacheVPU::Start(MIPSAnalyst::AnalysisResults &stats) {
 	}
 }
 
-const PPCReg *PpcRegCacheVPU::GetMIPSAllocationOrder(int &count) {
+const PPCReg *PpcRegCacheVPU::GetMIPSAllocationOrder(int &count) const {
 	// Note that R0 is reserved as scratch for now.
 	// R1 could be used as it's only used for scratch outside "regalloc space" now.
 	// R12 is also potentially usable.
diff --git a/Core/MIPS/PPC/PpcRegCacheVPU.h b/Core/MIPS/PPC/PpcRegCacheVPU.h
index 6ebf8356a6..eaf836eec8 100644
--- a/Core/MIPS/PPC/PpcRegCacheVPU.h
+++ b/Core/MIPS/PPC/PpcRegCacheVPU.h
@@ -89,8 +89,8 @@ public:
 	int GetMipsRegOffset(MIPSReg r);
 
 private:
-	const PPCReg *GetMIPSAllocationOrder(int &count);
-		
+	const PPCReg *GetMIPSAllocationOrder(int &count) const;
+
 	MIPSState *mips_;
 	MIPSComp::PpcJitOptions *options_;
 	PPCXEmitter *emit_;
diff --git a/GPU/Common/IndexGenerator.cpp b/GPU/Common/IndexGenerator.cpp
index 7a20129ad8..f0ab7e462a 100644
--- a/GPU/Common/IndexGenerator.cpp
+++ b/GPU/Common/IndexGenerator.cpp
@@ -45,7 +45,7 @@ bool IndexGenerator::PrimCompatible(int prim1, int prim2) {
 	return indexedPrimitiveType[prim1] == indexedPrimitiveType[prim2];
 }
 
-bool IndexGenerator::PrimCompatible(int prim) {
+bool IndexGenerator::PrimCompatible(int prim) const {
 	if (prim_ == GE_PRIM_INVALID)
 		return true;
 	return indexedPrimitiveType[prim] == prim_;
diff --git a/GPU/Common/IndexGenerator.h b/GPU/Common/IndexGenerator.h
index de56df064e..f30de3d1e3 100644
--- a/GPU/Common/IndexGenerator.h
+++ b/GPU/Common/IndexGenerator.h
@@ -27,7 +27,7 @@ public:
 	void Setup(u16 *indexptr);
 	void Reset();
 	static bool PrimCompatible(int prim1, int prim2);
-	bool PrimCompatible(int prim);
+	bool PrimCompatible(int prim) const;
 	GEPrimitiveType Prim() const { return prim_; }
 
 	void AddPrim(int prim, int vertexCount);
diff --git a/GPU/GPUState.h b/GPU/GPUState.h
index 178fe11d07..55bb87bb57 100644
--- a/GPU/GPUState.h
+++ b/GPU/GPUState.h
@@ -276,13 +276,13 @@ struct GPUgstate
 
 	// Alpha Test
 	bool isAlphaTestEnabled() const { return alphaTestEnable & 1; }
-	GEComparison getAlphaTestFunction() { return static_cast<GEComparison>(alphatest & 0x7); }
+	GEComparison getAlphaTestFunction() const { return static_cast<GEComparison>(alphatest & 0x7); }
 	int getAlphaTestRef() const { return (alphatest >> 8) & 0xFF; }
 	int getAlphaTestMask() const { return (alphatest >> 16) & 0xFF; }
 	
 	// Color Test
 	bool isColorTestEnabled() const { return colorTestEnable & 1; }
-	GEComparison getColorTestFunction() { return static_cast<GEComparison>(colortest & 0x3); }
+	GEComparison getColorTestFunction() const { return static_cast<GEComparison>(colortest & 0x3); }
 	u32 getColorTestRef() const { return colorref & 0xFFFFFF; }
 	u32 getColorTestMask() const { return colortestmask & 0xFFFFFF; }
 
@@ -305,7 +305,7 @@ struct GPUgstate
 	u32 getClutAddress() const { return (clutaddr & 0x00FFFFFF) | ((clutaddrupper << 8) & 0x0F000000); }
 	int getClutLoadBytes() const { return (loadclut & 0x3F) * 32; }
 	int getClutLoadBlocks() const { return (loadclut & 0x3F); }
-	GEPaletteFormat getClutPaletteFormat() { return static_cast<GEPaletteFormat>(clutformat & 3); }
+	GEPaletteFormat getClutPaletteFormat() const { return static_cast<GEPaletteFormat>(clutformat & 3); }
 	int getClutIndexShift() const { return (clutformat >> 2) & 0x1F; }
 	int getClutIndexMask() const { return (clutformat >> 8) & 0xFF; }
 	int getClutIndexStartPos() const { return ((clutformat >> 16) & 0x1F) << 4; }