diff --git a/lib/png.js b/lib/png.js
index c00518d..8978867 100644
--- a/lib/png.js
+++ b/lib/png.js
@@ -19,6 +19,10 @@ export class PNG extends Stream {
     this.depth = undefined;
     this._grayscaleData = undefined;
     this._propData = undefined;
+    this._configPostParse = {
+      initGrayscaleData: options.initGrayscaleData,
+      initPropData: options.initPropData,
+    };
 
     this.data = this.width > 0 && this.height > 0 ?
       new Buffer(4 * this.width * this.height) : null;
@@ -38,16 +42,8 @@ export class PNG extends Stream {
     this._parser.on('gamma', this._gamma.bind(this));
     this._parser.on('parsed', function(data) {
       this.data = data;
-      this._grayscaleData = undefined;
-      this._propData = undefined;
-      if (options.initGrayscaleData) {
-        this.initGrayscaleData();
-      }
-      if (options.initPropData) {
-        const shrinkMin = options.initPropData.shrinkMin || false;
-        const shrinkMax = options.initPropData.shrinkMax || false;
-        this.initGrayscaleData(shrinkMin, shrinkMax);
-      }
+
+      this._postParsed();
       this.emit('parsed', data);
     }.bind(this));
 
@@ -56,6 +52,22 @@ export class PNG extends Stream {
     this._packer.on('end', this.emit.bind(this, 'end'));
     this._parser.on('close', this._handleClose.bind(this));
     this._packer.on('error', this.emit.bind(this, 'error'));
+
+    this._postParsed = this._postParsed.bind(this);
+  }
+
+  _postParsed() {
+    this._grayscaleData = undefined;
+    this._propData = undefined;
+    const { initGrayscaleData, initPropData } = this._configPostParse;
+    if (initGrayscaleData) {
+      this.initGrayscaleData();
+    }
+    if (initPropData) {
+      const shrinkMin = initPropData.shrinkMin || false;
+      const shrinkMax = initPropData.shrinkMax || false;
+      this.initPropData(shrinkMin, shrinkMax);
+    }
   }
 
   pack() {
@@ -73,14 +85,11 @@ export class PNG extends Stream {
 
   parse(data, callback) {
     if (callback) {
-      var onParsed, onError;
+      let onParsed, onError;
 
-      onParsed = function(parsedData) {
+      onParsed = function() {
         this.removeListener('error', onError);
 
-        this.data = parsedData;
-        this._grayscaleData = undefined;
-        this._propData = undefined;
         callback(null, this);
       }.bind(this);