diff --git a/examples/kill_mem.js b/examples/kill_mem.js
new file mode 100644
index 0000000..c9d765c
--- /dev/null
+++ b/examples/kill_mem.js
@@ -0,0 +1,26 @@
+var 
+  sys = require("sys"),
+  jefe = new require("../lib/jefe"),
+  elJefe = new jefe.Jefe(),
+  scriptName = "script that creates too much memory should be killed";
+
+var sourceCode = "A = []; while (true) A.push('a')";
+
+elJefe.compile(scriptName, sourceCode, { maxMem: 10240, maxTime: 0 } );     // KB
+
+sys.error("this will kill the script for using too much memory regardless of how long it takes ...");
+
+elJefe.run(scriptName, {}, function (error, sandboxIn, sandboxOut) {
+  if (error) {
+    sys.puts("error = " + error);
+  } else {
+    sys.puts("completed without error");
+    sys.puts("sandboxOut = " + JSON.stringify(sandboxOut));
+  }
+
+  var stats = elJefe.getScriptStats(scriptName);
+  sys.p(stats);
+
+  process.exit(0);
+});
+
diff --git a/examples/while_true.js b/examples/while_true.js
index b6ab279..afbf773 100644
--- a/examples/while_true.js
+++ b/examples/while_true.js
@@ -6,7 +6,7 @@ var
 
 elJefe.compile(scriptName, "while (true) {}", { maxTime: 5000 } );
 
-sys.error("this will wait up to 5s ...");
+sys.error("this will wait up to 5s before killing the script ...");
 
 elJefe.run(scriptName, {}, function (error, sandboxIn, sandboxOut) {
   if (error) {
diff --git a/lib/jefe.js b/lib/jefe.js
index 8631b26..45bd41d 100644
--- a/lib/jefe.js
+++ b/lib/jefe.js
@@ -229,12 +229,27 @@ Jefe.prototype._runRequestOnChild = function (request, childHandler) {
 };
 
 Jefe.prototype._watchMem = function (request, childHandler, initialMem, initialMemPercent) {
-  var self = this;
+  var 
+    self = this,
+    script = request.script;
 
   function checkMem() {
     childHandler.peakMemoryUsage(function (err, mem, memPercent) {
       if ((script.maxMem        > 0 && mem        - initialMem        > script.maxMem) ||
           (script.maxMemPercent > 0 && memPercent - initialMemPercent > script.maxMemPercent)) {
+
+        if (common.debugMode) {
+          sys.debug("pid " + childHandler.pid + 
+                    " mem overage! maxMem=" + script.maxMem + 
+                    " initialMem=" + initialMem + 
+                    " currPeak=" + mem + 
+                    " deltaMem=" + (mem - initialMem) +
+                    " maxMemPercent=" + script.maxMemPercent + 
+                    " initialMemPercent=" + initialMemPercent + 
+                    " currPeakPercent=" + memPercent + 
+                    " deltaPercent=" + (memPercent - initialMemPercent));
+        }
+
         childHandler.kill();
         self.scripts[script.name].wasKilled("memory");
         request.callback(exports.ERR_TOO_MUCH_MEMORY, null);
diff --git a/lib/memory.js b/lib/memory.js
index d751898..f4e30d4 100644
--- a/lib/memory.js
+++ b/lib/memory.js
@@ -1,3 +1,5 @@
+var fs = require('fs');
+
 if (process.platform.match(/linux/i)) {
 
   /** 
@@ -28,7 +30,8 @@ if (process.platform.match(/linux/i)) {
         var 
           match = contents.match(/^VmHWM:\s+(\d+)\s+kB$/m),
           peakRSS = match ? parseInt(match[1], 10) : 0,
-          peakRSSPercent = (peakRSS > 0 && systemMemoryTotal > 0) ? peakRSS / systemMemoryTotal : 0;
+          peakRSSPercent = (peakRSS > 0 && exports.systemMemoryTotal > 0) 
+            ? peakRSS / exports.systemMemoryTotal : 0;
 
         callback(null, peakRSS, peakRSSPercent);
       }
diff --git a/lib/userscript.js b/lib/userscript.js
index ef48e1c..b532421 100644
--- a/lib/userscript.js
+++ b/lib/userscript.js
@@ -28,7 +28,7 @@ function UserScript(name, sourceCode, options) {
   if (this.maxMemPercent < 0 || this.maxMemPercent > 1) 
     throw new Error("maxMemPercent");
 
-  this.maxTime = Math.max(0, opts.maxTime || 250);
+  this.maxTime = Math.max(0, opts.maxTime === undefined ? 250 : opts.maxTime);
 
   this.name = name || '';
   this.sourceCode = sourceCode;