diff --git a/lib/ClassBuilder.js b/lib/ClassBuilder.js
index 164fd86..fb657c8 100644
--- a/lib/ClassBuilder.js
+++ b/lib/ClassBuilder.js
@@ -623,7 +623,7 @@ exports.prototype.createConcreteCtor = function( cname, members )
         attachInstanceId( this, ++_self._instanceId );
 
         // call the constructor, if one was provided
-        if ( this.__construct instanceof Function )
+        if ( typeof this.__construct === 'function' )
         {
             // note that since 'this' refers to the new class (even
             // subtypes), and since we're using apply with 'this', the
@@ -747,7 +747,7 @@ exports.prototype._attachPropInit = function(
         // first initialize the parent's properties, so that ours will overwrite
         // them
         var parent_init = prototype.___$$parent$$.__initProps;
-        if ( parent_init instanceof Function )
+        if ( typeof parent_init === 'function' )
         {
             // call the parent prop_init, letting it know that it's been
             // inherited so that it does not initialize private members or
diff --git a/lib/util.js b/lib/util.js
index 5d69505..eb5e738 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -323,7 +323,7 @@ exports.propParse = function( data, options )
             );
         }
         // method
-        else if ( value instanceof Function )
+        else if ( typeof value === 'function' )
         {
             callbackMethod.call(
                 callbackMethod,
@@ -381,7 +381,7 @@ exports.createAbstractMethod = function()
  */
 exports.isAbstractMethod = function( func )
 {
-    return ( ( func instanceof Function ) && ( func.abstractFlag === true ) )
+    return ( ( typeof func === 'function') && ( func.abstractFlag === true ) )
         ? true
         : false
     ;