diff --git a/swh/model/identifiers.py b/swh/model/identifiers.py
--- a/swh/model/identifiers.py
+++ b/swh/model/identifiers.py
@@ -7,6 +7,8 @@
 import datetime
 from functools import lru_cache
 
+from .exceptions import ValidationError
+from .fields.hashes import validate_sha1
 from .hashutil import hash_data, hash_git_data, DEFAULT_ALGORITHMS
 from .hashutil import hash_to_hex
 
@@ -603,7 +605,7 @@
 
     Args:
         type (str): Object's type
-        object (str): Object's dict representation
+        object (dict): Object's dict representation
         version (int): persistent identifier version (default to 1)
 
     Returns:
@@ -637,12 +639,21 @@
     return 'swh:%s:%s:%s' % (version, o['short_name'], _hash)
 
 
+PERSISTENT_IDENTIFIER_TYPES = ['snp', 'rel', 'rev', 'dir', 'cnt']
+
 PERSISTENT_IDENTIFIER_KEYS = [
     'namespace', 'scheme_version', 'object_type', 'object_id', 'metadata']
 
 PERSISTENT_IDENTIFIER_PARTS_SEP = ';'
 
 
+class SWHMalformedIdentifierException(ValueError):
+    """Exception when a string representing an identifier is badly formatted.
+
+    """
+    pass
+
+
 def parse_persistent_identifier(persistent_id):
     """Parse swh's :ref:`persistent-identifiers` scheme.
 
@@ -659,14 +670,47 @@
             * metadata, holding dict value
 
     """
+    # <pid>;<contextual-information>
     persistent_id_parts = persistent_id.split(PERSISTENT_IDENTIFIER_PARTS_SEP)
-    data = persistent_id_parts.pop(0).split(':')
+    pid_data = persistent_id_parts.pop(0).split(':')
+
+    if len(pid_data) != 4:
+        raise SWHMalformedIdentifierException(
+            'Wrong format: There should be 4 mandatory parameters')
+
+    # Checking for parsing errors
+    _ns, _version, _type, _id = pid_data
+    if _ns != 'swh':
+        raise SWHMalformedIdentifierException(
+            'Wrong format: Supported namespace is \'swh\'')
+
+    if _version != '1':
+        raise SWHMalformedIdentifierException(
+            'Wrong format: Supported version is 1')
+
+    expected_types = PERSISTENT_IDENTIFIER_TYPES
+    if _type not in expected_types:
+        raise SWHMalformedIdentifierException(
+            'Wrong format: Supported types are %s' % (
+                ', '.join(expected_types)))
+
+    if not _id:
+        raise SWHMalformedIdentifierException(
+            'Wrong format: Identifier should be present')
+
+    try:
+        validate_sha1(_id)
+    except ValidationError:
+        raise SWHMalformedIdentifierException(
+           'Wrong format: Identifier should be a valid hash')
+
     persistent_id_metadata = {}
     for part in persistent_id_parts:
         try:
             key, val = part.split('=')
             persistent_id_metadata[key] = val
         except Exception:
-            pass
-    data.append(persistent_id_metadata)
-    return dict(zip(PERSISTENT_IDENTIFIER_KEYS, data))
+            msg = 'Contextual data is badly formatted, form key=val expected'
+            raise SWHMalformedIdentifierException(msg)
+    pid_data.append(persistent_id_metadata)
+    return dict(zip(PERSISTENT_IDENTIFIER_KEYS, pid_data))
diff --git a/swh/model/tests/test_identifiers.py b/swh/model/tests/test_identifiers.py
--- a/swh/model/tests/test_identifiers.py
+++ b/swh/model/tests/test_identifiers.py
@@ -804,8 +804,8 @@
         for pid, _type, _version, _hash in [
                 ('swh:1:cnt:94a9ed024d3859793618152ea559a168bbcbb5e2', 'cnt',
                  '1', '94a9ed024d3859793618152ea559a168bbcbb5e2'),
-                ('swh:2:dir:d198bc9d7a6bcf6db04f476d29314f157507d505', 'dir',
-                 '2', 'd198bc9d7a6bcf6db04f476d29314f157507d505'),
+                ('swh:1:dir:d198bc9d7a6bcf6db04f476d29314f157507d505', 'dir',
+                 '1', 'd198bc9d7a6bcf6db04f476d29314f157507d505'),
                 ('swh:1:rev:309cf2674ee7a0749978cf8265ab91a60aea0f7d', 'rev',
                  '1', '309cf2674ee7a0749978cf8265ab91a60aea0f7d'),
                 ('swh:1:rel:22ece559cc7cc2364edc5e5593d63ae8bd229f9f', 'rel',
@@ -834,9 +834,7 @@
                   'dir', '1', '0b6959356d30f1a4e9b7f6bca59b9a336464c03d',
                  {
                      'origin': 'deb://Debian/packages/linuxdoc-tools'
-                 }),
-                 ('swh:1:dir:0b6959356d30f1a4e9b7f6bca59b9a336464c03d;invalid;malformed', # noqa
-                  'dir', '1', '0b6959356d30f1a4e9b7f6bca59b9a336464c03d', {})
+                 })
         ]:
             expected_result = {
                 'namespace': 'swh',
@@ -847,3 +845,34 @@
             }
             actual_result = identifiers.parse_persistent_identifier(pid)
             self.assertEquals(actual_result, expected_result)
+
+    def test_parse_persistent_identifier_parsing_error(self):
+        from swh.model.identifiers import (SWHMalformedIdentifierException,
+                                           PERSISTENT_IDENTIFIER_TYPES)
+        for pid, _error in [
+                ('swh:1:cnt',
+                 'Wrong format: There should be 4 mandatory parameters'),
+                ('swh:1:',
+                 'Wrong format: There should be 4 mandatory parameters'),
+                ('swh:',
+                 'Wrong format: There should be 4 mandatory parameters'),
+                ('swh:1:cnt:',
+                 'Wrong format: Identifier should be present'),
+                ('foo:1:cnt:abc8bc9d7a6bcf6db04f476d29314f157507d505',
+                 'Wrong format: Supported namespace is \'swh\''),
+                ('swh:2:dir:def8bc9d7a6bcf6db04f476d29314f157507d505',
+                 'Wrong format: Supported version is 1'),
+                ('swh:1:foo:fed8bc9d7a6bcf6db04f476d29314f157507d505',
+                 'Wrong format: Supported types are %s' % (
+                     ', '.join(PERSISTENT_IDENTIFIER_TYPES))),
+                ('swh:1:dir:0b6959356d30f1a4e9b7f6bca59b9a336464c03d;invalid;'
+                 'malformed',
+                 'Contextual data is badly formatted, form key=val expected'),
+                ('swh:1:snp:gh6959356d30f1a4e9b7f6bca59b9a336464c03d',
+                 'Wrong format: Identifier should be a valid hash'),
+                ('swh:1:snp:foo',
+                 'Wrong format: Identifier should be a valid hash')
+        ]:
+            with self.assertRaisesRegex(
+                    SWHMalformedIdentifierException, _error):
+                identifiers.parse_persistent_identifier(pid)