diff --git a/papaparse.js b/papaparse.js
index c3e3e56..d8e883b 100644
--- a/papaparse.js
+++ b/papaparse.js
@@ -193,7 +193,21 @@
 	function CsvToJson(_input, _config)
 	{
 		_config = _config || {};
-		_config.dynamicTyping = new DynamicTypingConfig(_config.dynamicTyping);
+        var dynamicTyping = _config.dynamicTyping || false;
+        debugger;
+        if (typeof dynamicTyping == 'function') {
+            _config.dynamicTypingFunction = dynamicTyping;
+            // Will be filled on first row call
+            dynamicTyping = {};
+        }
+        _config.dynamicTyping = dynamicTyping;
+        _config.shouldApplyDynamicTyping = function(field) {
+            // Cache function values to avoid calling it for each row
+            if (_config.dynamicTypingFunction && !_config.dynamicTyping[field]) {
+                _config.dynamicTyping[field] = _config.dynamicTypingFunction(field);
+            }
+            return (_config.dynamicTyping[field] || _config.dynamicTyping) === true
+        }
 
 		if (_config.worker && Papa.WORKERS_SUPPORTED)
 		{
@@ -415,24 +429,6 @@
 		}
 	}
 
-	function DynamicTypingConfig(config)
-	{
-		this._config = config;
-	}
-	DynamicTypingConfig.prototype.constructor = DynamicTypingConfig;
-	DynamicTypingConfig.prototype.isIncluded = function(field)
-	{
-		if (typeof this._config === 'function')
-		{
-			return this._config(field) === true;
-		}
-		if (typeof this._config === 'object')
-		{
-			return this._config[field] === true;
-		}
-		return !!this._config;
-	};
-
 	/** ChunkStreamer is the base prototype for various streamer implementations. */
 	function ChunkStreamer(config)
 	{
@@ -987,7 +983,7 @@
 
 		function parseDynamic(field, value)
 		{
-			if (_config.dynamicTyping.isIncluded(field))
+			if (_config.shouldApplyDynamicTyping(field))
 			{
 				if (value === 'true' || value === 'TRUE')
 					return true;