diff --git a/lib/ClassBuilder.js b/lib/ClassBuilder.js
index 369d664..9dd9555 100644
--- a/lib/ClassBuilder.js
+++ b/lib/ClassBuilder.js
@@ -244,16 +244,14 @@ exports.isInstanceOf = function( type, instance )
         return false;
     }
 
-    try
+    // check prototype chain (will throw an error if type is not a
+    // constructor (function)
+    if ( ( typeof type === 'function' )
+        && ( instance instanceof type )
+    )
     {
-        // check prototype chain (will throw an error if type is not a
-        // constructor (function)
-        if ( instance instanceof type )
-        {
-            return true;
-        }
+        return true;
     }
-    catch ( e ) {}
 
     // if no metadata is available, then our remaining checks cannot be
     // performed