diff --git a/CHANGELOG.md b/CHANGELOG.md
index f380db6..0fd36cd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,14 @@
+## 0.4.0 (2021-06-06)
+
+### Feat
+
+- **protocols**: add EntanglementProtocol
+
+### Fix
+
+- **QiskitBackend**: correct configuration_dict entry for max_qubits
+- **QuantumBitGenerator**: raise error if _refill_cache fails
+
 ## 0.3.0 (2021-06-03)
 
 ### Refactor
diff --git a/QRAND.bib b/QRAND.bib
index 05873b1..c274b31 100644
--- a/QRAND.bib
+++ b/QRAND.bib
@@ -3,7 +3,7 @@ @software{pedro_rivero_qrand
   title        = {QRAND: A multiprotocol and multiplatform quantum random number generation framework},
   year         = 2020,
   publisher    = {Zenodo},
-  version      = {0.3.0},
+  version      = {0.4.0},
   doi          = {10.5281/zenodo.4755731},
   url          = {https://doi.org/10.5281/zenodo.4755731}
 }
diff --git a/pyproject.toml b/pyproject.toml
index a49305b..29cc0d1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,7 +11,7 @@ exclude = '''
 name = "cz_conventional_commits"
 bump_message = "bump: version $current_version → $new_version"
 version_format = "$version"
-version = "0.3.0"
+version = "0.4.0"
 version_files = [
     "qrand/__init__.py:__version__",
     "tests/test_qrand.py:__version__",
@@ -41,7 +41,7 @@ line_length = 79
 
 [tool.poetry]
 name = "qrand"
-version = "0.3.0"
+version = "0.4.0"
 description = "A multiprotocol and multiplatform quantum random number generation framework"
 readme = "README.md"
 homepage = "https://github.com/pedrorrivero/qrand"
diff --git a/qrand/__init__.py b/qrand/__init__.py
index 45c3457..70d76ad 100644
--- a/qrand/__init__.py
+++ b/qrand/__init__.py
@@ -23,7 +23,7 @@
 __author__ = "Pedro Rivero"
 __copyright__ = "Copyright (c) 2021 Pedro Rivero"
 __license__ = "Apache-2.0"
-__version__ = "0.3.0"
+__version__ = "0.4.0"
 
 from ._qiskit_bit_generator import QiskitBitGenerator
 from .qrng import Qrng
diff --git a/tests/test_qrand.py b/tests/test_qrand.py
index e24b5ec..3e7bbfa 100644
--- a/tests/test_qrand.py
+++ b/tests/test_qrand.py
@@ -30,7 +30,7 @@
 ## VERSION
 ###############################################################################
 def test_version():
-    assert __version__ == "0.3.0"
+    assert __version__ == "0.4.0"
 
 
 ###############################################################################