diff --git a/fuji_server/harvester/metadata_harvester.py b/fuji_server/harvester/metadata_harvester.py
index ea930054..fff9626b 100644
--- a/fuji_server/harvester/metadata_harvester.py
+++ b/fuji_server/harvester/metadata_harvester.py
@@ -476,13 +476,13 @@ def parse_signposting_http_link_format(self, signposting_link_format_text):
             for link_prop in parsed_link[1:]:
                 link_prop = str(link_prop).strip()
                 if link_prop.startswith('anchor'):
-                    anchor_match = re.search('anchor\s*=\s*\"?([^,;"]+)\"?', link_prop)
+                    anchor_match = re.search(r'anchor\s*=\s*\"?([^,;"]+)\"?', link_prop)
                 if link_prop.startswith('rel'):
-                    rel_match = re.search('rel\s*=\s*\"?([^,;"]+)\"?', link_prop)
+                    rel_match = re.search(r'rel\s*=\s*\"?([^,;"]+)\"?', link_prop)
                 elif link_prop.startswith('type'):
-                    type_match = re.search('type\s*=\s*\"?([^,;"]+)\"?', link_prop)
+                    type_match = re.search(r'type\s*=\s*\"?([^,;"]+)\"?', link_prop)
                 elif link_prop.startswith('formats'):
-                    formats_match = re.search('formats\s*=\s*\"?([^,;"]+)\"?', link_prop)
+                    formats_match = re.search(r'formats\s*=\s*\"?([^,;"]+)\"?', link_prop)
             if type_match:
                 found_type = type_match[1]
             if rel_match:
diff --git a/fuji_server/helper/identifier_helper.py b/fuji_server/helper/identifier_helper.py
index d95bc561..b0647b61 100644
--- a/fuji_server/helper/identifier_helper.py
+++ b/fuji_server/helper/identifier_helper.py
@@ -121,7 +121,7 @@ def __init__(self, idstring, logger = None):
                 #workaround to identify arks properly:
                 self.identifier = self.identifier.replace('/ark:' , '/ark:/' )
                 self.identifier = self.identifier.replace('/ark://', '/ark:/')
-                generic_identifiers_org_pattern = '^([a-z0-9\._]+):(.+)'
+                generic_identifiers_org_pattern = r'^([a-z0-9\._]+):(.+)'
 
                 if self.is_uuid():
                     self.identifier_schemes = ['uuid']
diff --git a/fuji_server/helper/metadata_collector_xml.py b/fuji_server/helper/metadata_collector_xml.py
index 60b84a9b..a3bbfe5f 100644
--- a/fuji_server/helper/metadata_collector_xml.py
+++ b/fuji_server/helper/metadata_collector_xml.py
@@ -314,7 +314,7 @@ def get_mapped_xml_metadata(self, tree, mapping):
                         res[prop] = propcontent[0].get('tree').text
                     else:
                         res[prop] = lxml.etree.tostring(propcontent[0].get('tree'), method='text', encoding='unicode')
-                        res[prop] = re.sub('\s+', ' ', res[prop])
+                        res[prop] = re.sub(r'\s+', ' ', res[prop])
                         res[prop] = res[prop].strip()
                 else:
                     for propelem in propcontent:
@@ -324,7 +324,7 @@ def get_mapped_xml_metadata(self, tree, mapping):
                             res[prop].append(propelem.get('tree').text)
                         else:
                             resprop = lxml.etree.tostring(propelem.get('tree'), method='text', encoding='unicode')
-                            resprop = re.sub('\s+', ' ', resprop)
+                            resprop = re.sub(r'\s+', ' ', resprop)
                             resprop = resprop.strip()
                             res[prop].append(resprop)