diff --git a/pkgs/development/python-modules/langchain-core/default.nix b/pkgs/development/python-modules/langchain-core/default.nix
index 0903e6d2d509..9226ed18530e 100644
--- a/pkgs/development/python-modules/langchain-core/default.nix
+++ b/pkgs/development/python-modules/langchain-core/default.nix
@@ -17,6 +17,7 @@
   typing-extensions,
 
   # tests
+  blockbuster,
   freezegun,
   grandalf,
   httpx,
@@ -32,31 +33,22 @@
 
 buildPythonPackage rec {
   pname = "langchain-core";
-  version = "0.3.49";
+  version = "0.3.56";
   pyproject = true;
 
   src = fetchFromGitHub {
     owner = "langchain-ai";
     repo = "langchain";
     tag = "langchain-core==${version}";
-    hash = "sha256-s1vZ7G6Wzywf3euwX/RdCPkgzxvZTYVG0udGpHTIiQc=";
+    hash = "sha256-gsjYr22Phb71oKN4iVGsi6r1iETDhFHCKKOiwp0SuLU=";
   };
 
   sourceRoot = "${src.name}/libs/core";
 
-  patches = [
-    # Remove dependency on blockbuster (not available in nixpkgs due to dependency on forbiddenfruit)
-    ./rm-blockbuster.patch
-  ];
-
   build-system = [ pdm-backend ];
 
   pythonRelaxDeps = [ "tenacity" ];
 
-  pythonRemoveDependencies = [
-    "blockbuster"
-  ];
-
   dependencies = [
     jsonpatch
     langsmith
@@ -73,6 +65,7 @@ buildPythonPackage rec {
   doCheck = false;
 
   nativeCheckInputs = [
+    blockbuster
     freezegun
     grandalf
     httpx
diff --git a/pkgs/development/python-modules/langchain-core/rm-blockbuster.patch b/pkgs/development/python-modules/langchain-core/rm-blockbuster.patch
deleted file mode 100644
index a7dc2af18af4..000000000000
--- a/pkgs/development/python-modules/langchain-core/rm-blockbuster.patch
+++ /dev/null
@@ -1,155 +0,0 @@
-diff --git a/pyproject.toml b/pyproject.toml
-index a2cfc7adf..db37bd74a 100644
---- a/pyproject.toml
-+++ b/pyproject.toml
-@@ -53,7 +53,7 @@ test = [
-     "responses<1.0.0,>=0.25.0",
-     "pytest-socket<1.0.0,>=0.7.0",
-     "pytest-xdist<4.0.0,>=3.6.1",
--    "blockbuster~=1.5.18",
-+    # "blockbuster~=1.5.18",
-     "numpy<2.0.0,>=1.24.0; python_version < \"3.12\"",
-     "numpy<3,>=1.26.0; python_version >= \"3.12\"",
-     "langchain-tests",
-diff --git a/tests/unit_tests/conftest.py b/tests/unit_tests/conftest.py
-index 6438c3037..aa301c337 100644
---- a/tests/unit_tests/conftest.py
-+++ b/tests/unit_tests/conftest.py
-@@ -5,35 +5,35 @@ from importlib import util
- from uuid import UUID
- 
- import pytest
--from blockbuster import BlockBuster, blockbuster_ctx
-+# from blockbuster import BlockBuster, blockbuster_ctx
- from pytest import Config, Function, Parser
- from pytest_mock import MockerFixture
- 
- 
--@pytest.fixture(autouse=True)
--def blockbuster() -> Iterator[BlockBuster]:
--    with blockbuster_ctx("langchain_core") as bb:
--        for func in ["os.stat", "os.path.abspath"]:
--            (
--                bb.functions[func]
--                .can_block_in("langchain_core/_api/internal.py", "is_caller_internal")
--                .can_block_in("langchain_core/runnables/base.py", "__repr__")
--                .can_block_in(
--                    "langchain_core/beta/runnables/context.py", "aconfig_with_context"
--                )
--            )
--
--        for func in ["os.stat", "io.TextIOWrapper.read"]:
--            bb.functions[func].can_block_in(
--                "langsmith/client.py", "_default_retry_config"
--            )
--
--        for bb_function in bb.functions.values():
--            bb_function.can_block_in(
--                "freezegun/api.py", "_get_cached_module_attributes"
--            )
--
--        yield bb
-+# @pytest.fixture(autouse=True)
-+# def blockbuster() -> Iterator[BlockBuster]:
-+#     with blockbuster_ctx("langchain_core") as bb:
-+#         for func in ["os.stat", "os.path.abspath"]:
-+#             (
-+#                 bb.functions[func]
-+#                 .can_block_in("langchain_core/_api/internal.py", "is_caller_internal")
-+#                 .can_block_in("langchain_core/runnables/base.py", "__repr__")
-+#                 .can_block_in(
-+#                     "langchain_core/beta/runnables/context.py", "aconfig_with_context"
-+#                 )
-+#             )
-+
-+#         for func in ["os.stat", "io.TextIOWrapper.read"]:
-+#             bb.functions[func].can_block_in(
-+#                 "langsmith/client.py", "_default_retry_config"
-+#             )
-+
-+#         for bb_function in bb.functions.values():
-+#             bb_function.can_block_in(
-+#                 "freezegun/api.py", "_get_cached_module_attributes"
-+#             )
-+
-+#         yield bb
- 
- 
- def pytest_addoption(parser: Parser) -> None:
-diff --git a/tests/unit_tests/language_models/chat_models/test_rate_limiting.py b/tests/unit_tests/language_models/chat_models/test_rate_limiting.py
-index ee6eefba9..4d39da58d 100644
---- a/tests/unit_tests/language_models/chat_models/test_rate_limiting.py
-+++ b/tests/unit_tests/language_models/chat_models/test_rate_limiting.py
-@@ -2,17 +2,17 @@ import time
- from typing import Optional as Optional
- 
- import pytest
--from blockbuster import BlockBuster
-+# from blockbuster import BlockBuster
- 
- from langchain_core.caches import InMemoryCache
- from langchain_core.language_models import GenericFakeChatModel
- from langchain_core.rate_limiters import InMemoryRateLimiter
- 
- 
--@pytest.fixture(autouse=True)
--def deactivate_blockbuster(blockbuster: BlockBuster) -> None:
--    # Deactivate BlockBuster to not disturb the rate limiter timings
--    blockbuster.deactivate()
-+# @pytest.fixture(autouse=True)
-+# def deactivate_blockbuster(blockbuster: BlockBuster) -> None:
-+#     # Deactivate BlockBuster to not disturb the rate limiter timings
-+#     blockbuster.deactivate()
- 
- 
- def test_rate_limit_invoke() -> None:
-diff --git a/tests/unit_tests/runnables/test_runnable_events_v2.py b/tests/unit_tests/runnables/test_runnable_events_v2.py
-index e1e1f37b9..21d2f1600 100644
---- a/tests/unit_tests/runnables/test_runnable_events_v2.py
-+++ b/tests/unit_tests/runnables/test_runnable_events_v2.py
-@@ -15,7 +15,7 @@ from typing import (
- )
- 
- import pytest
--from blockbuster import BlockBuster
-+# from blockbuster import BlockBuster
- from pydantic import BaseModel
- 
- from langchain_core.callbacks import CallbackManagerForRetrieverRun, Callbacks
-@@ -2005,7 +2005,7 @@ EXPECTED_EVENTS = [
- 
- async def test_sync_in_async_stream_lambdas(blockbuster: BlockBuster) -> None:
-     """Test invoking nested runnable lambda."""
--    blockbuster.deactivate()
-+    # blockbuster.deactivate()
- 
-     def add_one(x: int) -> int:
-         return x + 1
-diff --git a/tests/unit_tests/test_setup.py b/tests/unit_tests/test_setup.py
-index 1df3c73a2..58e94de9a 100644
---- a/tests/unit_tests/test_setup.py
-+++ b/tests/unit_tests/test_setup.py
-@@ -1,15 +1,15 @@
- import time
- 
- import pytest
--from blockbuster import BlockingError
-+# from blockbuster import BlockingError
- 
- from langchain_core import sys_info
- 
- 
--async def test_blockbuster_setup() -> None:
--    """Check if blockbuster is correctly setup."""
--    # Blocking call outside of langchain_core is allowed.
--    time.sleep(0.01)  # noqa: ASYNC251
--    with pytest.raises(BlockingError):
--        # Blocking call from langchain_core raises BlockingError.
--        sys_info.print_sys_info()
-+# async def test_blockbuster_setup() -> None:
-+#     """Check if blockbuster is correctly setup."""
-+#     # Blocking call outside of langchain_core is allowed.
-+#     time.sleep(0.01)  # noqa: ASYNC251
-+#     with pytest.raises(BlockingError):
-+#         # Blocking call from langchain_core raises BlockingError.
-+#         sys_info.print_sys_info()