diff --git a/public/vm/bytecode-parser.js b/public/vm/bytecode-parser.js
index 0abe875..1804c86 100644
--- a/public/vm/bytecode-parser.js
+++ b/public/vm/bytecode-parser.js
@@ -24,10 +24,33 @@ function getBytes(data) {
 
 }
 
+function getLineNumbers(data) {
+    var string_data = data.toString();
+
+    // Strip all the comments for easier parsing
+    var without_comments = string_data.replace(new RegExp("#.*", "gi"), "");
+
+    // Each byte should now be a pair of two hex digits.
+    // Put all these in an array.
+    var lines = without_comments.split("\n");
+    var line_numbers = [];
+    for (var line_number = 0; line_number < lines.length; line_number++ ) {
+        lines[line_number].replace(
+            new RegExp("([0123456789ABCDEF][0123456789ABCDEF])", "gi"),
+            function(next_byte) {
+                // +1 because lines start at 1, for some weird reason.
+                // Who doesn't start counting at 0?
+                line_numbers.push(line_number+1);
+            });
+    }
+    return line_numbers;
+}
+
 var FunctionInfo = function (stream) {
     this.num_args = stream.get_u2();
     this.num_vars = stream.get_u2();
     this.code_length = stream.get_u2();
+    this.code_byte_offset = stream.index;
     this.code = stream.get_bytes(this.code_length);
 }
 
@@ -36,8 +59,9 @@ var NativeInfo = function (stream) {
     this.function_table_index = stream.get_u2();
 }
 
-var Bc0File = function (filename) {
-    var file = getBytes(filename);
+var Bc0File = function (bytecode) {
+    var file = getBytes(bytecode);
+    this.line_numbers = getLineNumbers(bytecode);
     var stream = new byte_stream.ByteStream(file);
     
     var magic = stream.get_u4();
@@ -95,6 +119,12 @@ Bc0File.prototype.string_from_index = function (i) {
     return result;
 }
 
+Bc0File.prototype.line_for_indices = function(function_index, byte_offset) {
+    var offset_in_file = this.function_pool[function_index].code_byte_offset + 
+        byte_offset;
+    return this.line_numbers[offset_in_file];
+}
+
 function parse(bytecode) {
     return new Bc0File(bytecode);
 }
diff --git a/public/vm/c0vm.js b/public/vm/c0vm.js
index 2e9ae9d..267df54 100755
--- a/public/vm/c0vm.js
+++ b/public/vm/c0vm.js
@@ -115,9 +115,10 @@ ProgramState.prototype.doIf = function(f) {
 }
 
 ProgramState.prototype.step = function() {
+    this.maintain_line_numbers();
     var opcode = this.frame.program[this.frame.pc]
     log("0x" + this.frame.pc.toString(16) + " Running opcode " +
-        op.lookup_table[opcode]);
+        op.lookup_table[opcode] + " at line " + this.bytecode_line);
     switch (opcode) {
         // Stack manipulation
     case op.POP:
@@ -473,6 +474,12 @@ ProgramState.prototype.step = function() {
     }
 }
 
+ProgramState.prototype.maintain_line_numbers = function() {
+    this.bytecode_line = this.file.line_for_indices(this.frame.function_id,
+                                                    this.frame.pc);
+    // this.c0_line = SOMEHOW GET THE LINE IN THE c0 FILE
+}
+
 ProgramState.prototype.remove_breakpoint = function(opcode_index) {
     if (opcode_index < 0){
         console.log("Error: negative opcode_index" + opcode_index.toString());
@@ -514,14 +521,17 @@ ProgramState.prototype.run = function() {
             
             if (this.frame.function_id == breakpoint[0] &&
                 this.frame.pc == breakpoint[1] &&
-                this.stoppedAt !== breakpoint) {
+                this.stopped_at !== breakpoint) {
                 log("Breakpoint reached!");
-                this.stoppedAt = breakpoint;
+                this.stopped_at = breakpoint;
+
+                this.maintain_line_numbers();
+
                 return this;
             }
         }
 
-        this.stoppedAt = undefined;
+        this.stopped_at = undefined;
         
         var val = this.step();
         if (val !== undefined) return val;
diff --git a/test/tests.js b/test/tests.js
index abbcd2e..0cc7f39 100644
--- a/test/tests.js
+++ b/test/tests.js
@@ -121,7 +121,12 @@ exports.testBREAKPOINT1 = function(test) {
     test.ok(vm.frame.stack[0] == 23 &&
             vm.frame.stack[1] == 19,
             "VM stack incorrect");
+
+    test.ok(vm.bytecode_line == 19,
+            "VM reports incorrect line in bytecode: " + vm.bytecode_line);
+    
     result = vm.run();
-    test.ok(result == 1748, "VM did not resume operation correctly, gave result " + result);
+    test.ok(result == 1748,
+            "VM did not resume operation correctly, gave result " + result);
     test.done();
 }