diff --git a/lib/smalloc.js b/lib/smalloc.js
index cba96ac8df..fa1bf23155 100644
--- a/lib/smalloc.js
+++ b/lib/smalloc.js
@@ -30,25 +30,33 @@ exports.dispose = dispose;
 // don't allow kMaxLength to accidentally be overwritten. it's a lot less
 // apparent when a primitive is accidentally changed.
 Object.defineProperty(exports, 'kMaxLength', {
-  writable: false,
-  value: kMaxLength
+  enumerable: true,
+  value: kMaxLength,
+  writable: false
 });
 
 
 function alloc(n, obj) {
-  n = ~~n;
+  n = n >>> 0;
 
+  if (util.isUndefined(obj))
+    obj = {};
+  else if (util.isPrimitive(obj))
+    throw new TypeError('obj must be an Object');
   if (n > kMaxLength)
     throw new RangeError('n > kMaxLength');
   if (util.isArray(obj))
     throw new TypeError('Arrays are not supported');
 
-  return smalloc.alloc(util.isUndefined(obj) ? {} : obj, n);
+  return smalloc.alloc(obj, n);
 }
 
 
 function dispose(obj) {
+  if (util.isPrimitive(obj))
+    throw new TypeError('obj must be an Object');
   if (util.isBuffer(obj))
     throw new TypeError('obj cannot be a Buffer');
+
   smalloc.dispose(obj);
 }
diff --git a/test/simple/test-smalloc.js b/test/simple/test-smalloc.js
index 3729adba3e..ceba0a4f5d 100644
--- a/test/simple/test-smalloc.js
+++ b/test/simple/test-smalloc.js
@@ -107,6 +107,12 @@ assert.throws(function() {
 }, RangeError);
 
 
+// properly convert to uint32 before checking overflow
+assert.throws(function() {
+  alloc(-1);
+}, RangeError);
+
+
 // no allocating on what's been allocated
 assert.throws(function() {
   alloc(1, alloc(1));
@@ -123,6 +129,9 @@ assert.throws(function() {
 assert.throws(function() {
   alloc(1, true);
 }, TypeError);
+assert.throws(function() {
+  alloc(1, null);
+}, TypeError);
 
 
 // should not throw allocating to most objects
@@ -186,3 +195,17 @@ var b = alloc(5, {});
 dispose(b);
 for (var i = 0; i < 5; i++)
   assert.equal(b[i], undefined);
+
+
+// verify dispose throws properly
+
+// only allow object to be passed to dispose
+assert.throws(function() {
+  alloc.dispose(null);
+});
+
+
+// can't dispose a Buffer
+assert.throws(function() {
+  alloc.dispose(new Buffer());
+});