diff --git a/cpu.js b/cpu.js
index 3acd443..8974daa 100644
--- a/cpu.js
+++ b/cpu.js
@@ -29,6 +29,14 @@ const CPU = {
     CPU.memory = new Uint8Array(256);
     CPU.memory.set(data, 0);
   },
+  incrementIP: (offset) => {
+    CPU.previousIP = CPU.IP;
+    CPU.IP = CPU.IP + offset;
+  },
+  setIP: (address) => {
+    CPU.previousIP = CPU.IP;
+    CPU.IP = address;
+  },
   setFlagOverflow: () => { CPU.FLAGS |= 4 },
   setFlagNegative: () => { CPU.FLAGS |= 4 },
   setFlagZero:     () => { CPU.FLAGS |= 2 },
@@ -49,6 +57,7 @@ const CPU = {
   },
 
   // Debug info
+  previousIP: 0,
   currentInstruction: {
     opcode: null,
     operand: null,
@@ -64,19 +73,19 @@ const Instructions = {
   end: () => {
     CPU.currentInstruction.mnemonic = 'END';
     CPU.running = false;
-    CPU.IP = CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   store_lit: (lit) => {
     CPU.currentInstruction.mnemonic = 'STO lit';
     CPU.memory[lit] = CPU.Acc;
-    CPU.IP = CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   store_addr: (addr) => {
     CPU.currentInstruction.mnemonic = 'STO addr';
     CPU.memory[CPU.memory[addr]] = CPU.Acc;
-    CPU.IP = CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   load_lit: (lit) => {
@@ -84,7 +93,7 @@ const Instructions = {
     CPU.Acc = lit;
     CPU.updateFlagNegative();
     CPU.updateFlagZero();
-    CPU.IP = CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   load_addr: (addr) => {
@@ -92,7 +101,7 @@ const Instructions = {
     CPU.Acc = CPU.memory[addr];
     CPU.updateFlagNegative();
     CPU.updateFlagZero();
-    CPU.IP = CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   add_lit: (lit) => {
@@ -117,7 +126,7 @@ const Instructions = {
     CPU.Acc = sum;
     CPU.updateFlagNegative();
     CPU.updateFlagZero();
-    CPU.IP = CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   add_addr: (addr) => {
@@ -142,7 +151,7 @@ const Instructions = {
     CPU.Acc = sum;
     CPU.updateFlagNegative();
     CPU.updateFlagZero();
-    CPU.IP = CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   sub_lit: (lit) => {
@@ -167,7 +176,7 @@ const Instructions = {
     CPU.Acc = sum;
     CPU.updateFlagNegative();
     CPU.updateFlagZero();
-    CPU.IP = CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   sub_addr: (addr) => {
@@ -192,35 +201,35 @@ const Instructions = {
     CPU.Acc = sum;
     CPU.updateFlagNegative();
     CPU.updateFlagZero();
-    CPU.IP = CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   hop_lit: (lit) => {
     CPU.currentInstruction.mnemonic = `HOP lit;  IP+2: ${CPU.memory[CPU.IP+2]}, IP+3: ${CPU.memory[CPU.IP+3]}`;
     if (CPU.Acc === lit) {
-      CPU.IP += 4;
+      CPU.incrementIP(4);
     } else {
-      CPU.IP += 2;
+      CPU.incrementIP(2);
     }
   },
 
   hop_addr: (addr) => {
     CPU.currentInstruction.mnemonic = 'HOP addr';
     if (CPU.Acc === CPU.memory[addr]) {
-      CPU.IP += 4;
+      CPU.incrementIP(4);
     } else {
-      CPU.IP += 2;
+      CPU.incrementIP(2);
     }
   },
 
   jump_lit: (lit) => {
     CPU.currentInstruction.mnemonic = 'JMP lit';
-    CPU.IP = lit;
+    CPU.setIP(lit);
   },
 
   jump_addr: (addr) => {
     CPU.currentInstruction.mnemonic = 'JMP addr';
-    CPU.IP = CPU.memory[addr];
+    CPU.setIP(CPU.memory[addr]);
   },
 
   flag_toggle: (flagNum) => {
@@ -232,7 +241,7 @@ const Instructions = {
     if (flagNum === 3) { mask = 8; }
     if (mask === null) { throw new Error('Invalid flag number'); }
     CPU.FLAGS = CPU.FLAGS ^= mask;
-    CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 
   flag_hop: (flagNum) => {
@@ -244,15 +253,15 @@ const Instructions = {
     if (flagNum === 3) { mask = 8; }
     if (mask === null) { throw new Error('Invalid flag number'); }
     if (CPU.FLAGS & mask) {
-      CPU.IP += 4;
+      CPU.incrementIP(4);
     } else {
-      CPU.IP += 2;
+      CPU.incrementIP(2);
     }
   },
 
   no_op: () => {
     CPU.currentInstruction.mnemonic = `NOP`;
-    CPU.IP += 2;
+    CPU.incrementIP(2);
   },
 }
 
@@ -385,7 +394,7 @@ function logCPUState(debugInfo, debug = false) {
       display.prettyPrintDisplay(CPU.memory);
     }
     console.log();
-    console.log(`Line ${debugInfo[CPU.IP-2].lineNumber}: ${debugInfo[CPU.IP-2].source}`);
+    console.log(`Line ${debugInfo[CPU.previousIP].lineNumber}: ${debugInfo[CPU.previousIP].source}`);
     console.log('Mnemonic:', CPU.currentInstruction.mnemonic);
     console.log(`Machine:  $${num2hex(CPU.currentInstruction.opcode)} $${num2hex(CPU.currentInstruction.operand)}`);
     console.log();