diff --git a/common/include/Pcsx2Defs.h b/common/include/Pcsx2Defs.h
index 6e23feb18e..b077ea8a29 100644
--- a/common/include/Pcsx2Defs.h
+++ b/common/include/Pcsx2Defs.h
@@ -54,14 +54,14 @@ extern "C" unsigned __int64 __xgetbv(int);
 #		ifdef _MSC_VER
 #			define jASSUME(exp) (__assume(exp))
 #		else
-#			define jASSUME(exp) ((void) sizeof(exp))
+#			define jASSUME(exp) do { if(!(exp)) __builtin_unreachable(); } while(0)
 #		endif
 #	else
 #		define jBREAKPOINT() __debugbreak();
 #		ifdef wxASSERT
 #			define jASSUME(exp) wxASSERT(exp)
 #		else
-#			define jASSUME(exp) do { if(exp) ; else jBREAKPOINT(); } while(0);
+#			define jASSUME(exp) do { if(!(exp)) jBREAKPOINT(); } while(0)
 #		endif
 #	endif
 #endif
diff --git a/common/include/Utilities/Assertions.h b/common/include/Utilities/Assertions.h
index e0a4e7f5cc..0f268d028e 100644
--- a/common/include/Utilities/Assertions.h
+++ b/common/include/Utilities/Assertions.h
@@ -117,8 +117,8 @@ extern pxDoAssertFnType* pxDoAssert;
 #	define pxAssumeMsg(cond, msg)	pxAssumeRel(cond, msg)
 #	define pxAssumeDev(cond, msg)	pxAssumeRel(cond, msg)
 
-#	define pxFail(msg)				pxAssertMsg(false, msg)
-#	define pxFailDev(msg)			pxAssertDev(false, msg)
+#	define pxFail(msg)              pxAssertMsg(false, msg)
+#	define pxFailDev(msg)           pxAssertDev(false, msg)
 
 #elif defined(PCSX2_DEVBUILD)
 
@@ -141,8 +141,8 @@ extern pxDoAssertFnType* pxDoAssert;
 #	define pxAssumeMsg(cond, msg)	pxAssumeRel(cond, msg) //(__assume(cond))
 #	define pxAssumeDev(cond, msg)	pxAssumeRel(cond, msg)
 
-#	define pxFail(msg)				pxAssertDev(false, msg)
-#	define pxFailDev(msg)			pxAssertDev(false, msg)
+#	define pxFail(msg)              pxAssertDev(false, msg)
+#	define pxFailDev(msg)           pxAssertDev(false, msg)
 
 #else
 
@@ -155,8 +155,8 @@ extern pxDoAssertFnType* pxDoAssert;
 #	define pxAssumeMsg(cond, msg)	(__assume(cond))
 #	define pxAssumeDev(cond, msg)	(__assume(cond))
 
-#	define pxFail(msg)				do{} while(0)
-#	define pxFailDev(msg)			do{} while(0)
+#	define pxFail(msg)              do{} while(0)
+#	define pxFailDev(msg)           do{} while(0)
 
 #endif
 
diff --git a/pcsx2/Counters.cpp b/pcsx2/Counters.cpp
index c6a0ac5cc6..1eb8557caa 100644
--- a/pcsx2/Counters.cpp
+++ b/pcsx2/Counters.cpp
@@ -68,7 +68,7 @@ void rcntReset(int index) {
 static __fi void _rcntSet( int cntidx )
 {
 	s32 c;
-	jASSUME( cntidx <= 4 );		// rcntSet isn't valid for h/vsync counters.
+	pxAssume( cntidx <= 4 );		// rcntSet isn't valid for h/vsync counters.
 
 	const Counter& counter = counters[cntidx];
 
diff --git a/pcsx2/IopCounters.cpp b/pcsx2/IopCounters.cpp
index b6e69c7a37..454063273c 100644
--- a/pcsx2/IopCounters.cpp
+++ b/pcsx2/IopCounters.cpp
@@ -542,7 +542,7 @@ __fi void psxRcntWmode16( int index, u32 value )
 {
 	PSXCNT_LOG( "IOP Counter[%d] writeMode = 0x%04X", index, value );
 
-	jASSUME( index >= 0 && index < 3 );
+	pxAssume( index >= 0 && index < 3 );
 	psxCounter& counter = psxCounters[index];
 
 	counter.mode  = value;
@@ -603,7 +603,7 @@ __fi void psxRcntWmode32( int index, u32 value )
 {
 	PSXCNT_LOG( "IOP Counter[%d] writeMode = 0x%04x", index, value );
 
-	jASSUME( index >= 3 && index < 6 );
+	pxAssume( index >= 3 && index < 6 );
 	psxCounter& counter = psxCounters[index];
 
 	counter.mode  = value;
diff --git a/pcsx2/R5900.cpp b/pcsx2/R5900.cpp
index dfd71b54ec..29ff799766 100644
--- a/pcsx2/R5900.cpp
+++ b/pcsx2/R5900.cpp
@@ -261,7 +261,7 @@ __fi void cpuSetEvent()
 
 __fi void cpuClearInt( uint i )
 {
-	jASSUME( i < 32 );
+	pxAssume( i < 32 );
 	cpuRegs.interrupt &= ~(1 << i);
 }
 
diff --git a/pcsx2/ps2/Iop/IopHwRead.cpp b/pcsx2/ps2/Iop/IopHwRead.cpp
index f1c4a0ab77..4603eb5bd9 100644
--- a/pcsx2/ps2/Iop/IopHwRead.cpp
+++ b/pcsx2/ps2/Iop/IopHwRead.cpp
@@ -29,7 +29,7 @@ using namespace Internal;
 mem8_t __fastcall iopHwRead8_Page1( u32 addr )
 {
 	// all addresses are assumed to be prefixed with 0x1f801xxx:
-	jASSUME( (addr >> 12) == 0x1f801 );
+	pxAssume( (addr >> 12) == 0x1f801 );
 
 	u32 masked_addr = addr & 0x0fff;
 
@@ -81,7 +81,7 @@ mem8_t __fastcall iopHwRead8_Page1( u32 addr )
 mem8_t __fastcall iopHwRead8_Page3( u32 addr )
 {
 	// all addresses are assumed to be prefixed with 0x1f803xxx:
-	jASSUME( (addr >> 12) == 0x1f803 );
+	pxAssume( (addr >> 12) == 0x1f803 );
 
 	mem8_t ret;
 	if( addr == 0x1f803100 )	// PS/EE/IOP conf related
@@ -98,7 +98,7 @@ mem8_t __fastcall iopHwRead8_Page3( u32 addr )
 mem8_t __fastcall iopHwRead8_Page8( u32 addr )
 {
 	// all addresses are assumed to be prefixed with 0x1f808xxx:
-	jASSUME( (addr >> 12) == 0x1f808 );
+	pxAssume( (addr >> 12) == 0x1f808 );
 
 	mem8_t ret;
 
@@ -117,10 +117,10 @@ template< typename T >
 static __fi T _HwRead_16or32_Page1( u32 addr )
 {
 	// all addresses are assumed to be prefixed with 0x1f801xxx:
-	jASSUME( (addr >> 12) == 0x1f801 );
+	pxAssume( (addr >> 12) == 0x1f801 );
 
 	// all addresses should be aligned to the data operand size:
-	jASSUME(
+	pxAssume(
 		( sizeof(T) == 2 && (addr & 1) == 0 ) ||
 		( sizeof(T) == 4 && (addr & 3) == 0 )
 	);
@@ -385,7 +385,7 @@ mem16_t __fastcall iopHwRead16_Page1( u32 addr )
 mem16_t __fastcall iopHwRead16_Page3( u32 addr )
 {
 	// all addresses are assumed to be prefixed with 0x1f803xxx:
-	jASSUME( (addr >> 12) == 0x1f803 );
+	pxAssume( (addr >> 12) == 0x1f803 );
 
 	mem16_t ret = psxHu16(addr);
 	IopHwTraceLog<mem16_t>( addr, ret, true );
@@ -397,7 +397,7 @@ mem16_t __fastcall iopHwRead16_Page3( u32 addr )
 mem16_t __fastcall iopHwRead16_Page8( u32 addr )
 {
 	// all addresses are assumed to be prefixed with 0x1f808xxx:
-	jASSUME( (addr >> 12) == 0x1f808 );
+	pxAssume( (addr >> 12) == 0x1f808 );
 
 	mem16_t ret = psxHu16(addr);
 	IopHwTraceLog<mem16_t>( addr, ret, true );
@@ -416,7 +416,7 @@ mem32_t __fastcall iopHwRead32_Page1( u32 addr )
 mem32_t __fastcall iopHwRead32_Page3( u32 addr )
 {
 	// all addresses are assumed to be prefixed with 0x1f803xxx:
-	jASSUME( (addr >> 12) == 0x1f803 );
+	pxAssume( (addr >> 12) == 0x1f803 );
 	const mem32_t ret = psxHu32(addr);
 	IopHwTraceLog<mem32_t>( addr, ret, true );
 	return ret;
@@ -427,7 +427,7 @@ mem32_t __fastcall iopHwRead32_Page3( u32 addr )
 mem32_t __fastcall iopHwRead32_Page8( u32 addr )
 {
 	// all addresses are assumed to be prefixed with 0x1f808xxx:
-	jASSUME( (addr >> 12) == 0x1f808 );
+	pxAssume( (addr >> 12) == 0x1f808 );
 
 	u32 masked_addr = addr & 0x0fff;
 	mem32_t ret;
diff --git a/pcsx2/x86/ix86-32/iR5900LoadStore.cpp b/pcsx2/x86/ix86-32/iR5900LoadStore.cpp
index 8126aeb64c..e602e4b17b 100644
--- a/pcsx2/x86/ix86-32/iR5900LoadStore.cpp
+++ b/pcsx2/x86/ix86-32/iR5900LoadStore.cpp
@@ -105,7 +105,7 @@ void SetFastMemory(int bSetFast)
 //
 void recLoad64( u32 bits, bool sign )
 {
-	jASSUME( bits == 64 || bits == 128 );
+	pxAssume( bits == 64 || bits == 128 );
 
 	// Load EDX with the destination.
 	// 64/128 bit modes load the result directly into the cpuRegs.GPR struct.
@@ -147,7 +147,7 @@ void recLoad64( u32 bits, bool sign )
 //
 void recLoad32( u32 bits, bool sign )
 {
-	jASSUME( bits <= 32 );
+	pxAssume( bits <= 32 );
 
 	// 8/16/32 bit modes return the loaded value in EAX.
 
diff --git a/pcsx2/x86/ix86-32/recVTLB.cpp b/pcsx2/x86/ix86-32/recVTLB.cpp
index 120814045d..df13f4e69e 100644
--- a/pcsx2/x86/ix86-32/recVTLB.cpp
+++ b/pcsx2/x86/ix86-32/recVTLB.cpp
@@ -339,7 +339,7 @@ void vtlb_dynarec_init()
 //                            Dynarec Load Implementations
 void vtlb_DynGenRead64(u32 bits)
 {
-	jASSUME( bits == 64 || bits == 128 );
+	pxAssume( bits == 64 || bits == 128 );
 
 	uptr* writeback = DynGen_PrepRegs();
 
@@ -355,7 +355,7 @@ void vtlb_DynGenRead64(u32 bits)
 //   Returns read value in eax.
 void vtlb_DynGenRead32(u32 bits, bool sign)
 {
-	jASSUME( bits <= 32 );
+	pxAssume( bits <= 32 );
 
 	uptr* writeback = DynGen_PrepRegs();
 
diff --git a/plugins/GSdx/stdafx.h b/plugins/GSdx/stdafx.h
index 80181cb3e4..bec5ec3e00 100644
--- a/plugins/GSdx/stdafx.h
+++ b/plugins/GSdx/stdafx.h
@@ -204,7 +204,7 @@ using namespace std;
         #include "assert.h"
         #define __forceinline __inline__ __attribute__((always_inline,unused))
         // #define __forceinline __inline__ __attribute__((__always_inline__,__gnu_inline__))
-        #define __assume(c) ((void)0)
+        #define __assume(c) do { if (!(c)) __builtin_unreachable(); } while(0)
 
     #endif
 
diff --git a/plugins/zerogs/opengl/common/PS2Etypes.h b/plugins/zerogs/opengl/common/PS2Etypes.h
index 5091291d9a..b1226e333d 100644
--- a/plugins/zerogs/opengl/common/PS2Etypes.h
+++ b/plugins/zerogs/opengl/common/PS2Etypes.h
@@ -32,25 +32,10 @@
 #define CALLBACK    __stdcall
 #endif
 
-
-// jASSUME - give hints to the optimizer
-//  This is primarily useful for the default case switch optimizer, which enables VC to
-//  generate more compact switches.
-
-#ifdef NDEBUG
-#	define jBREAKPOINT() ((void) 0)
-#	ifdef _MSC_VER
-#		define jASSUME(exp) (__assume(exp))
-#	else
-#		define jASSUME(exp) ((void) sizeof(exp))
-#	endif
+#ifdef _MSC_VER
+#define UNREACHABLE_CODE __assume(0)
 #else
-#	if defined(_MSC_VER)
-#		define jBREAKPOINT() do { __asm int 3 } while(0)
-#	else
-#		define jBREAKPOINT() ((void) *(volatile char *) 0)
-#	endif
-#	define jASSUME(exp) if(exp) ; else jBREAKPOINT()
+#define UNREACHABLE_CODE __builtin_unreachable()
 #endif
 
 // disable the default case in a switch
@@ -59,7 +44,7 @@
 	break; \
 	\
 default: \
-	jASSUME(0); \
+	UNREACHABLE_CODE; \
 	break; \
 }