diff --git a/.drone/test1.lpf b/.drone/test1.lpf
index 8b761d1..7785158 100644
--- a/.drone/test1.lpf
+++ b/.drone/test1.lpf
@@ -1 +1 @@
-{"xzoom":100,"yzoom":485,"xmin":-1,"ymax":1,"xaxisstep":"1","yaxisstep":"0.1","xaxislabel":"ω (rad/s)","yaxislabel":"G (dB)","logscalex":false,"linewidth":2,"showxgrad":true,"showygrad":true,"textsize":22,"history":[[["EditedProperty",["h","Function","labelX",3,2.5,false]],["EditedProperty",["h","Function","labelPosition","above-left","above",false]],["EditedProperty",["h","Function","labelPosition","above","left",false]],["EditedProperty",["h","Function","labelX",2.5,2,false]],["EditedProperty",["h","Function","labelX",2,2.2,false]],["EditedProperty",["h","Function","labelX",2.2,9,false]]],[]],"width":1908,"height":1011,"objects":{"Sequence":[["u",true,"#ff5500","name + value",true,true,{"1":"cos(u[n])"},{"0":"-1"},"above-left",8]],"Function":[["f",true,"#2b156d","name + value","integral((x + 1), x, \"cos (t)\", \"t\")","ℝ⁺*","ℝ","application","left",7,true,true],["g",true,"#ac539c","name + value","0.739083","ℝ","ℝ","application","below",-1,true,false],["h",true,"#00aa00","name + value","derivative(\"cos t\", \"t\", x)","ℤ","ℝ","application","left",9,true,true]],"Repartition":[["X",true,"#1E1EAF","name",true,true,{"0":"0.2","1":"0.1","2":"0.2"},"above",2.5]],"Point":[["A",true,"#060759","name + value","4","(-0.5)","top","●"]]},"type":"logplotv1"}
\ No newline at end of file
+LPFv1{"xzoom":100,"yzoom":485,"xmin":-1,"ymax":1,"xaxisstep":"1","yaxisstep":"0.1","xaxislabel":"ω (rad/s)","yaxislabel":"G (dB)","logscalex":false,"linewidth":2,"showxgrad":true,"showygrad":true,"textsize":22,"history":[[["EditedProperty",["h","Function","labelX",3,2.5,false]],["EditedProperty",["h","Function","labelPosition","above-left","above",false]],["EditedProperty",["h","Function","labelPosition","above","left",false]],["EditedProperty",["h","Function","labelX",2.5,2,false]],["EditedProperty",["h","Function","labelX",2,2.2,false]],["EditedProperty",["h","Function","labelX",2.2,9,false]]],[]],"width":1908,"height":1005,"objects":{"Sequence":[["u",true,"#ff5500","name + value",true,true,{"1":"cos(u[n])"},{"0":"-1"},"above-left",8]],"Function":[["f",true,"#2b156d","name + value","integral((x + 1), x, \"cos (t)\", \"t\")","ℝ⁺*","ℝ","application","left",7,true,true],["g",true,"#ac539c","name + value","0.739083","ℝ","ℝ","application","below",-1,true,false],["h",true,"#00aa00","name + value","derivative(\"cos t\", \"t\", x)","ℤ","ℝ","application","left",9,true,true]],"Repartition":[["X",true,"#1E1EAF","name",true,true,{"0":"0.2","1":"0.1","2":"0.2"},"above",2.5]],"Point":[["A",true,"#060759","name + value","4","(-0.5)","top","●"]]},"type":"logplotv1"}
\ No newline at end of file
diff --git a/LogarithmPlotter/__init__.py b/LogarithmPlotter/__init__.py
index 86e9579..0853e1f 100644
--- a/LogarithmPlotter/__init__.py
+++ b/LogarithmPlotter/__init__.py
@@ -25,13 +25,14 @@ from PySide2 import __version__ as PySide2_version
 import os
 import tempfile
 from platform import release as os_release
-from json import dumps
+from json import dumps, loads
 from sys import platform, argv, version as sys_version
 import webbrowser
 
 __VERSION__ = "0.0.1.dev0"
 
 tempfile = tempfile.mkstemp(suffix='.png')[1]
+pwd = os.getcwd()
 
 def get_linux_theme():
     des = {
@@ -50,19 +51,39 @@ class Helper(QObject):
 
     @Slot(str, str)
     def write(self, filename, filedata):
+        os.chdir(pwd)
         if os.path.exists(os.path.dirname(os.path.realpath(filename))):
+            if filename.split(".")[-1] == "lpf":
+                # Add header to file
+                filedata = "LPFv1" + filedata
             f = open(os.path.realpath(filename), 'w',  -1, 'utf8')
             f.write(filedata)
             f.close()
+        os.chdir(os.path.dirname(os.path.realpath(__file__)))
         
     @Slot(str, result=str)
     def load(self, filename):
+        os.chdir(pwd)
+        data = '{}'
         if os.path.exists(os.path.realpath(filename)):
             f = open(os.path.realpath(filename), 'r',  -1, 'utf8')
             data = f.read()
             f.close()
-            return data
-        return '{}'
+            try:
+                if data[:5] == "LPFv1":
+                    # V1 version of the file
+                    data = data[5:]
+                elif data[0] == "{" and "type" in loads(data) and loads(data)["type"] == "logplotv1":
+                    pass
+                else:
+                    raise Exception("Invalid LogarithmPlotter file.")
+            except Exception as e: # If file can't be loaded
+                from PySide2.QtWidgets import QMessageBox
+                QMessageBox.warning(None, 'LogarithmPlotter', 'Could not open file "{}":\n{}'.format(filename, e), QMessageBox.Ok) # Cannot parse file
+        else:
+            QMessageBox.warning(None, 'LogarithmPlotter', 'Could not open file: "{}"\nFile does not exist.'.format(filename), QMessageBox.Ok) # Cannot parse file
+        os.chdir(os.path.dirname(os.path.realpath(__file__)))
+        return data
 
     @Slot(result=str)
     def gettmpfile(self):
@@ -91,7 +112,6 @@ class Helper(QObject):
         webbrowser.open(url)
         
 def run():
-    pwd = os.getcwd()
     os.chdir(os.path.dirname(os.path.realpath(__file__)))
     
     os.environ["QT_QUICK_CONTROLS_STYLE"] = {
@@ -114,10 +134,8 @@ def run():
     engine.addImportPath(os.path.realpath(os.path.join(os.getcwd(), "qml")))
     engine.load(os.path.realpath(os.path.join(os.getcwd(), "qml", "eu", "ad5001", "LogarithmPlotter", "LogarithmPlotter.qml")))
 
-    os.chdir(pwd)
     if len(argv) > 0 and os.path.exists(argv[-1]) and argv[-1].split('.')[-1] in ['json', 'lgg', 'lpf']:
         engine.rootObjects()[0].loadDiagram(argv[-1])
-    os.chdir(os.path.dirname(os.path.realpath(__file__)))
 
     if not engine.rootObjects():
         print("No root object")