diff --git a/pkgs/development/python-modules/langchain/default.nix b/pkgs/development/python-modules/langchain/default.nix
index 39cb8a41908d..779b84440936 100644
--- a/pkgs/development/python-modules/langchain/default.nix
+++ b/pkgs/development/python-modules/langchain/default.nix
@@ -40,18 +40,23 @@
 
 buildPythonPackage rec {
   pname = "langchain";
-  version = "0.3.18";
+  version = "0.3.20";
   pyproject = true;
 
   src = fetchFromGitHub {
     owner = "langchain-ai";
     repo = "langchain";
     tag = "langchain==${version}";
-    hash = "sha256-oJ4lUbQqHNEqd9UdgLH0ZmTkdZpUbJ7UNsQyIrs8JvI=";
+    hash = "sha256-N209wUGdlHkOZynhSSE+ZHylL7cK+8H3PfZIG/wvMd0=";
   };
 
   sourceRoot = "${src.name}/libs/langchain";
 
+  patches = [
+    # blockbuster isn't supported in nixpkgs
+    ./rm-blockbuster.patch
+  ];
+
   build-system = [ pdm-backend ];
 
   buildInputs = [ bash ];
@@ -61,6 +66,10 @@ buildPythonPackage rec {
     "tenacity"
   ];
 
+  pythonRemoveDeps = [
+    "blockbuster"
+  ];
+
   dependencies = [
     aiohttp
     langchain-core
diff --git a/pkgs/development/python-modules/langchain/rm-blockbuster.patch b/pkgs/development/python-modules/langchain/rm-blockbuster.patch
new file mode 100644
index 000000000000..4022f17a9323
--- /dev/null
+++ b/pkgs/development/python-modules/langchain/rm-blockbuster.patch
@@ -0,0 +1,68 @@
+diff --git a/tests/unit_tests/conftest.py b/tests/unit_tests/conftest.py
+index fed8dbec5..6144ad7b8 100644
+--- a/tests/unit_tests/conftest.py
++++ b/tests/unit_tests/conftest.py
+@@ -5,36 +5,36 @@ from importlib import util
+ from typing import Dict, Sequence
+ 
+ import pytest
+-from blockbuster import blockbuster_ctx
++# from blockbuster import blockbuster_ctx
+ from pytest import Config, Function, Parser
+ 
+ 
+-@pytest.fixture(autouse=True)
+-def blockbuster() -> Iterator[None]:
+-    with blockbuster_ctx("langchain") as bb:
+-        bb.functions["io.TextIOWrapper.read"].can_block_in(
+-            "langchain/__init__.py", "<module>"
+-        )
+-
+-        for func in ["os.stat", "os.path.abspath"]:
+-            (
+-                bb.functions[func]
+-                .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
++# @pytest.fixture(autouse=True)
++# def blockbuster() -> Iterator[None]:
++#     with blockbuster_ctx("langchain") as bb:
++#         bb.functions["io.TextIOWrapper.read"].can_block_in(
++#             "langchain/__init__.py", "<module>"
++#         )
++
++#         for func in ["os.stat", "os.path.abspath"]:
++#             (
++#                 bb.functions[func]
++#                 .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
+ 
+ 
+ def pytest_addoption(parser: Parser) -> None: