diff --git a/SVM/Instructions/ADD.cs b/SVM/Instructions/ADD.cs
index 2014dcb..e20827c 100644
--- a/SVM/Instructions/ADD.cs
+++ b/SVM/Instructions/ADD.cs
@@ -34,7 +34,7 @@ namespace SVM.Instructions
         {
             Debug.Assert(vars.Length > 1);
             var reg = vars[0];
-            if (reg <= VM.REGISTERS)
+            if (reg > VM.REGISTERS)
             {
                 throw new Fault(FaultType.IllegalOp);
             }
diff --git a/SVM/Instructions/CLR.cs b/SVM/Instructions/CLR.cs
index c3867ea..fa26d8a 100644
--- a/SVM/Instructions/CLR.cs
+++ b/SVM/Instructions/CLR.cs
@@ -27,7 +27,7 @@ namespace SVM.Instructions
         {
             Debug.Assert(vars.Length == 1);
             byte reg = vars[0];
-            if (reg <= VM.REGISTERS)
+            if (reg > VM.REGISTERS)
             {
                 throw new Fault(FaultType.IllegalOp);
             }
diff --git a/SVM/Instructions/JBC.cs b/SVM/Instructions/JBC.cs
index b475784..99ed5a0 100644
--- a/SVM/Instructions/JBC.cs
+++ b/SVM/Instructions/JBC.cs
@@ -73,7 +73,7 @@ namespace SVM.Instructions
         {
             Debug.Assert(vars.Length == 4);
             byte reg = vars[0];
-            if (reg <= VM.REGISTERS)
+            if (reg > VM.REGISTERS)
             {
                 throw new Fault(FaultType.IllegalOp);
             }
diff --git a/SVM/Instructions/JZ.cs b/SVM/Instructions/JZ.cs
index 2e6acc2..d96c99c 100644
--- a/SVM/Instructions/JZ.cs
+++ b/SVM/Instructions/JZ.cs
@@ -47,7 +47,7 @@ namespace SVM.Instructions
         {
             Debug.Assert(vars.Length == 3);
             byte reg = vars[0];
-            if (reg <= VM.REGISTERS)
+            if (reg > VM.REGISTERS)
             {
                 throw new Fault(FaultType.IllegalOp);
             }
diff --git a/SVM/Instructions/LOAD.cs b/SVM/Instructions/LOAD.cs
index e8d2371..18b088b 100644
--- a/SVM/Instructions/LOAD.cs
+++ b/SVM/Instructions/LOAD.cs
@@ -47,7 +47,7 @@ namespace SVM.Instructions
         {
             Debug.Assert(vars.Length > 1);
             var reg = vars[0];
-            if (reg <= VM.REGISTERS)
+            if (reg > VM.REGISTERS)
             {
                 throw new Fault(FaultType.IllegalOp);
             }
diff --git a/SVM/Instructions/PUSH.cs b/SVM/Instructions/PUSH.cs
index 722ad4e..b63d42a 100644
--- a/SVM/Instructions/PUSH.cs
+++ b/SVM/Instructions/PUSH.cs
@@ -29,7 +29,7 @@ namespace SVM.Instructions
         {
             Debug.Assert(vars.Length == 1);
             var reg = vars[0];
-            if (reg <= VM.REGISTERS)
+            if (reg > VM.REGISTERS)
             {
                 throw new Fault(FaultType.IllegalOp);
             }
diff --git a/SVM/Instructions/SHL.cs b/SVM/Instructions/SHL.cs
index 8c37eb8..31dc93d 100644
--- a/SVM/Instructions/SHL.cs
+++ b/SVM/Instructions/SHL.cs
@@ -35,7 +35,7 @@ namespace SVM.Instructions
             byte reg = vars[0];
             byte bit = vars[1];
 
-            if (reg <= VM.REGISTERS)
+            if (reg > VM.REGISTERS)
             {
                 throw new Fault(FaultType.IllegalOp);
             }
diff --git a/SVM/PGM/FAULT.txt b/SVM/PGM/FAULT.txt
index 0ae94b3..ab1e198 100644
--- a/SVM/PGM/FAULT.txt
+++ b/SVM/PGM/FAULT.txt
@@ -20,10 +20,9 @@ ORIGIN 0x10
 			CALL :WRNL
 			RET
 
-:MAIN		LOAD A I0x0			# Set fault handler to 0x10
-			SAVE A F_FLTJH
-			LOAD A I0x10
-			SAVE A F_FLTJL
+:MAIN		LOAD A I0x10		# Set fault handler to 0x10
+			SAVEH A F_FLTJH
+			SAVEL A F_FLTJL
 			CLR A
 			BTS A 1
 			SAVE A F_FLTSTS		# Enable fault handler
diff --git a/SVM/VM.cs b/SVM/VM.cs
index a5c3649..49c733e 100644
--- a/SVM/VM.cs
+++ b/SVM/VM.cs
@@ -82,6 +82,7 @@ namespace SVM
         {
             if (RUN)
             {
+                var nextPC = PC++;
                 try
                 {
                     InstructionCount++;
@@ -89,8 +90,7 @@ namespace SVM
                     {
                         throw new Fault(FaultType.MemoryOverflow);
                     }
-                    var pc = PC;
-                    var op = MEM[PC++];
+                    var op = MEM[nextPC];
                     if (!instructions.ContainsKey(op))
                     {
                         throw new Fault(FaultType.UndefinedOp);
@@ -107,8 +107,9 @@ namespace SVM
                     if (!faultStatus.Trip(flt))
                     {
                         //Halt system as trip failed (already tripped or not enabled)
+                        var nextBytes = BitConverter.ToString(MEM.Subset(nextPC, 4)).Replace("-", " ");
                         Ports[0].Write(Encoding.ASCII.GetBytes(
-                            string.Format("Unhandled Fault [{0}] at 0x{1:X2}", flt.Type, PC)
+                            string.Format("Unhandled Fault [{0}] at 0x{1:X2}: next bytes {2}.", flt.Type, nextPC, nextBytes)
                             ));
                         RUN = false;
                     } else