diff --git a/swh/core/db/common.py b/swh/core/db/common.py
--- a/swh/core/db/common.py
+++ b/swh/core/db/common.py
@@ -7,6 +7,19 @@
 import functools
 
 
+def remove_kwargs(names):
+    def decorator(f):
+        sig = inspect.signature(f)
+        params = sig.parameters
+        params = [param for param in params.values()
+                  if param.name not in names]
+        sig = sig.replace(parameters=params)
+        f.__signature__ = sig
+        return f
+
+    return decorator
+
+
 def apply_options(cursor, options):
     """Applies the given postgresql client options to the given cursor.
 
@@ -33,6 +46,7 @@
             raise ValueError(
                     'Use db_transaction_generator for generator functions.')
 
+        @remove_kwargs(['cur', 'db'])
         @functools.wraps(meth)
         def _meth(self, *args, **kwargs):
             if 'cur' in kwargs and kwargs['cur']:
@@ -67,6 +81,7 @@
             raise ValueError(
                     'Use db_transaction for non-generator functions.')
 
+        @remove_kwargs(['cur', 'db'])
         @functools.wraps(meth)
         def _meth(self, *args, **kwargs):
             if 'cur' in kwargs and kwargs['cur']:
diff --git a/swh/core/db/tests/test_db.py b/swh/core/db/tests/test_db.py
--- a/swh/core/db/tests/test_db.py
+++ b/swh/core/db/tests/test_db.py
@@ -3,6 +3,7 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+import inspect
 import os.path
 import tempfile
 import unittest
@@ -151,6 +152,21 @@
                 yield None
 
 
+def test_db_transaction_signature():
+    """Checks db_transaction removes the 'cur' and 'db' arguments."""
+    def f(self, foo, *, bar=None):
+        pass
+    expected_sig = inspect.signature(f)
+
+    @db_transaction()
+    def g(self, foo, *, bar=None, db=None, cur=None):
+        pass
+
+    actual_sig = inspect.signature(g)
+
+    assert actual_sig == expected_sig
+
+
 def test_db_transaction_generator(mocker):
     expected_cur = object()
 
@@ -189,3 +205,18 @@
             @db_transaction_generator()
             def endpoint(self, cur=None, db=None):
                 pass
+
+
+def test_db_transaction_generator_signature():
+    """Checks db_transaction removes the 'cur' and 'db' arguments."""
+    def f(self, foo, *, bar=None):
+        pass
+    expected_sig = inspect.signature(f)
+
+    @db_transaction_generator()
+    def g(self, foo, *, bar=None, db=None, cur=None):
+        yield None
+
+    actual_sig = inspect.signature(g)
+
+    assert actual_sig == expected_sig