diff --git a/pyproject.toml b/pyproject.toml
index 15635a2a0a..1397c23e4f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -138,6 +138,12 @@ sphinx-gp-theme = false
 sphinx-ux-autodoc-layout = false
 sphinx-ux-badges = false
 
+[tool.uv.sources]
+# Temporary smoke-test pin against the libtmux 0.57.0 parity branch
+# (tmux-python/libtmux PR #672). Revert once 0.57.0 ships on PyPI and
+# the dependencies constraint bumps to >=0.57.0.
+libtmux = { git = "https://github.com/tmux-python/libtmux.git", branch = "parity-pt-2" }
+
 [tool.coverage.run]
 branch = true
 source = [
diff --git a/uv.lock b/uv.lock
index 5646e14f0b..322665f400 100644
--- a/uv.lock
+++ b/uv.lock
@@ -414,7 +414,7 @@ name = "exceptiongroup"
 version = "1.3.1"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
-    { name = "typing-extensions", marker = "python_full_version < '3.13'" },
+    { name = "typing-extensions", marker = "python_full_version < '3.11'" },
 ]
 sdist = { url = "https://files.pythonhosted.org/packages/50/79/66800aadf48771f6b62f7eb014e352e5d06856655206165d775e675a02c9/exceptiongroup-1.3.1.tar.gz", hash = "sha256:8b412432c6055b0b7d14c310000ae93352ed6754f70fa8f7c34141f91c4e3219", size = 30371, upload-time = "2025-11-21T23:01:54.787Z" }
 wheels = [
@@ -616,11 +616,7 @@ wheels = [
 [[package]]
 name = "libtmux"
 version = "0.56.0"
-source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/7d/62/896e1e0412dd76c88926604d5a231feb9b116d6f32abe19054e244504dbc/libtmux-0.56.0.tar.gz", hash = "sha256:bddf52214405e4f64850826d44cbc958d4a01c53432983cee0e2856bdbbaaedb", size = 476168, upload-time = "2026-05-10T13:40:23.774Z" }
-wheels = [
-    { url = "https://files.pythonhosted.org/packages/e9/ce/4319c912164fa142956c73ba50ed6f2aac2ca7cced2e96c8320114f1c937/libtmux-0.56.0-py3-none-any.whl", hash = "sha256:ddf70de0f287666fb0f02082732f28eed46450de1828c995da3de2b12042ab60", size = 97768, upload-time = "2026-05-10T13:40:22.189Z" },
-]
+source = { git = "https://github.com/tmux-python/libtmux.git?branch=parity-pt-2#81a021ed8de455ed97bb12ae4ba6adcda434da24" }
 
 [[package]]
 name = "linkify-it-py"
@@ -1668,7 +1664,7 @@ testing = [
 
 [package.metadata]
 requires-dist = [
-    { name = "libtmux", specifier = "~=0.56.0" },
+    { name = "libtmux", git = "https://github.com/tmux-python/libtmux.git?branch=parity-pt-2" },
     { name = "pyyaml", specifier = ">=6.0" },
 ]