diff --git a/Backend-libXML/Parser.py b/Backend-libXML/Parser.py
index f991b70..4cd5ac7 100644
--- a/Backend-libXML/Parser.py
+++ b/Backend-libXML/Parser.py
@@ -1,31 +1,18 @@
 from lxml import etree
 from io import BytesIO
 
-def prettify(source: str) -> str:
-    """Method used to pretty format given XML
 
-    :param source: XML
-    :return: prettified XML
+def format(source: str, prettify: bool) -> str:
+    """Method used to format XML
+
+    :param source: XML to format
+    :param prettify: sets if XML must be prettified 
+    (have added intendations etc.) or not
+    :return: formatted XML
     """
-    prolog = ""
-    prolog_start = source.find("<?")
-    
-    if prolog_start != -1:
-        prolog_end = source.find("?>") + 2
-        prolog = source[prolog_start:prolog_end] + "\n"
-        source = source[prolog_end: ]
-    
-    parser = etree.XMLParser(remove_blank_text=True)
-    xml = etree.fromstring(source, parser=parser)
-    return prolog + etree.tostring(xml, pretty_print=True).decode()
 
-def minimize(source: str) -> str:
-    """Method used to minimize XML by deleting not needed whitespaces.
-
-    :param source: XML
-    :return: minimized XML
-    """
-    
+    # Prolog is removed when XML is parsed
+    # so program has to copy it
     prolog = ""
     prolog_start = source.find("<?")
     
@@ -34,9 +21,14 @@ def minimize(source: str) -> str:
         prolog = source[prolog_start:prolog_end]
         source = source[prolog_end: ]
     
+    byte_input = BytesIO(source.encode("utf-8"))
     parser = etree.XMLParser(remove_blank_text=True)
-    xml = etree.fromstring(source, parser=parser)
-    return prolog + etree.tostring(xml, pretty_print=False).decode()
+    xml = etree.parse(byte_input, parser=parser)
+
+    if prettify:
+        prolog += "\n"
+
+    return prolog + etree.tostring(xml, pretty_print=prettify).decode()
 
 
 def xpath(source: str, xpath: str) -> str:
diff --git a/Backend-libXML/main.py b/Backend-libXML/main.py
index 117b089..d618dd2 100644
--- a/Backend-libXML/main.py
+++ b/Backend-libXML/main.py
@@ -74,9 +74,9 @@ def process_xml(request: request, type: str) -> str:
         elif (type == "xpath"):
             response_json['result'] = Parser.xpath(data, process)
         elif (type == "prettify"):
-            response_json['result'] = Parser.prettify(data)
+            response_json['result'] = Parser.format(data, True)
         elif (type == "minimize"):
-            response_json['result'] = Parser.minimize(data)
+            response_json['result'] = Parser.format(data, False)
         else:
             raise ValueError("Valid operation types are: xsd, xslt, xpath")