diff --git a/hatch_cpp/structs.py b/hatch_cpp/structs.py
index 75df2d8..5884988 100644
--- a/hatch_cpp/structs.py
+++ b/hatch_cpp/structs.py
@@ -102,8 +102,15 @@ def default() -> HatchCppPlatform:
             toolchain = "clang"
         elif "cl" in CC and "cl" in CXX:
             toolchain = "msvc"
+        # Fallback to platform defaults
+        elif platform == "linux":
+            toolchain = "gcc"
+        elif platform == "darwin":
+            toolchain = "clang"
+        elif platform == "win32":
+            toolchain = "msvc"
         else:
-            raise Exception(f"Unrecognized toolchain: {CC}, {CXX}")
+            toolchain = "gcc"
 
         # Customizations
         if which("ccache") and not environ.get("HATCH_CPP_DISABLE_CCACHE"):
@@ -117,6 +124,12 @@ def default() -> HatchCppPlatform:
         #     LD = which("ld.lld")
         return HatchCppPlatform(cc=CC, cxx=CXX, ld=LD, platform=platform, toolchain=toolchain)
 
+    @staticmethod
+    def platform_for_toolchain(toolchain: CompilerToolchain) -> HatchCppPlatform:
+        platform = HatchCppPlatform.default()
+        platform.toolchain = toolchain
+        return platform
+
     def get_compile_flags(self, library: HatchCppLibrary, build_type: BuildType = "release") -> str:
         flags = ""
 
@@ -241,11 +254,27 @@ class HatchCppBuildConfig(BaseModel):
     cmake: Optional[HatchCppCmakeConfiguration] = Field(default=None)
     platform: Optional[HatchCppPlatform] = Field(default_factory=HatchCppPlatform.default)
 
-    @model_validator(mode="after")
-    def check_toolchain_matches_args(self):
-        if self.cmake and self.libraries:
+    @model_validator(mode="wrap")
+    @classmethod
+    def validate_model(cls, data, handler):
+        if "toolchain" in data:
+            data["platform"] = HatchCppPlatform.platform_for_toolchain(data["toolchain"])
+            data.pop("toolchain")
+        elif "platform" not in data:
+            data["platform"] = HatchCppPlatform.default()
+        if "cc" in data:
+            data["platform"].cc = data["cc"]
+            data.pop("cc")
+        if "cxx" in data:
+            data["platform"].cxx = data["cxx"]
+            data.pop("cxx")
+        if "ld" in data:
+            data["platform"].ld = data["ld"]
+            data.pop("ld")
+        model = handler(data)
+        if model.cmake and model.libraries:
             raise ValueError("Must not provide libraries when using cmake toolchain.")
-        return self
+        return model
 
 
 class HatchCppBuildPlan(HatchCppBuildConfig):
diff --git a/hatch_cpp/tests/test_project_cmake/project/include/project/basic.hpp b/hatch_cpp/tests/test_project_cmake/project/include/project/basic.hpp
new file mode 100644
index 0000000..65cb62e
--- /dev/null
+++ b/hatch_cpp/tests/test_project_cmake/project/include/project/basic.hpp
@@ -0,0 +1,17 @@
+#pragma once
+#include "Python.h"
+
+PyObject* hello(PyObject*, PyObject*);
+
+static PyMethodDef extension_methods[] = {
+  {"hello", (PyCFunction)hello, METH_NOARGS},
+  {nullptr, nullptr, 0, nullptr}
+};
+
+static PyModuleDef extension_module = {
+  PyModuleDef_HEAD_INIT, "extension", "extension", -1, extension_methods};
+
+PyMODINIT_FUNC PyInit_extension(void) {
+  Py_Initialize();
+  return PyModule_Create(&extension_module);
+}
diff --git a/hatch_cpp/tests/test_project_override_toolchain/cpp/project/basic.cpp b/hatch_cpp/tests/test_project_override_toolchain/cpp/project/basic.cpp
new file mode 100644
index 0000000..db4432a
--- /dev/null
+++ b/hatch_cpp/tests/test_project_override_toolchain/cpp/project/basic.cpp
@@ -0,0 +1,5 @@
+#include "project/basic.hpp"
+
+PyObject* hello(PyObject*, PyObject*) {
+    return PyUnicode_FromString("A string");
+}
diff --git a/hatch_cpp/tests/test_project_override_toolchain/cpp/project/basic.hpp b/hatch_cpp/tests/test_project_override_toolchain/cpp/project/basic.hpp
new file mode 100644
index 0000000..65cb62e
--- /dev/null
+++ b/hatch_cpp/tests/test_project_override_toolchain/cpp/project/basic.hpp
@@ -0,0 +1,17 @@
+#pragma once
+#include "Python.h"
+
+PyObject* hello(PyObject*, PyObject*);
+
+static PyMethodDef extension_methods[] = {
+  {"hello", (PyCFunction)hello, METH_NOARGS},
+  {nullptr, nullptr, 0, nullptr}
+};
+
+static PyModuleDef extension_module = {
+  PyModuleDef_HEAD_INIT, "extension", "extension", -1, extension_methods};
+
+PyMODINIT_FUNC PyInit_extension(void) {
+  Py_Initialize();
+  return PyModule_Create(&extension_module);
+}
diff --git a/hatch_cpp/tests/test_project_override_toolchain/project/__init__.py b/hatch_cpp/tests/test_project_override_toolchain/project/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/hatch_cpp/tests/test_project_override_toolchain/pyproject.toml b/hatch_cpp/tests/test_project_override_toolchain/pyproject.toml
new file mode 100644
index 0000000..b5c40ca
--- /dev/null
+++ b/hatch_cpp/tests/test_project_override_toolchain/pyproject.toml
@@ -0,0 +1,38 @@
+[build-system]
+requires = ["hatchling>=1.20"]
+build-backend = "hatchling.build"
+
+[project]
+name = "hatch-cpp-test-project-toolchain"
+description = "Toolchain override test project for hatch-cpp"
+version = "0.1.0"
+requires-python = ">=3.9"
+dependencies = [
+    "hatchling>=1.20",
+    "hatch-cpp",
+]
+
+[tool.hatch.build]
+artifacts = [
+    "project/*.dll",
+    "project/*.dylib",
+    "project/*.so",
+]
+
+[tool.hatch.build.sources]
+src = "/"
+
+[tool.hatch.build.targets.sdist]
+packages = ["project"]
+
+[tool.hatch.build.targets.wheel]
+packages = ["project"]
+
+[tool.hatch.build.hooks.hatch-cpp]
+verbose = true
+libraries = [
+    {name = "project/extension", sources = ["cpp/project/basic.cpp"], include-dirs = ["cpp"]}
+]
+toolchain = "gcc"
+cc = "clang"
+cxx = "clang++"
diff --git a/hatch_cpp/tests/test_projects.py b/hatch_cpp/tests/test_projects.py
index 7553c04..dd4c6fc 100644
--- a/hatch_cpp/tests/test_projects.py
+++ b/hatch_cpp/tests/test_projects.py
@@ -13,6 +13,8 @@ class TestProject:
         [
             "test_project_basic",
             "test_project_override_classes",
+            "test_project_override_classes",
+            "test_project_override_toolchain",
             "test_project_pybind",
             "test_project_nanobind",
             "test_project_limited_api",
@@ -29,8 +31,7 @@ def test_basic(self, project):
         # compile
         check_call(
             [
-                "hatchling",
-                "build",
+                "hatch-build",
                 "--hooks-only",
             ],
             cwd=f"hatch_cpp/tests/{project}",
diff --git a/hatch_cpp/tests/test_structs.py b/hatch_cpp/tests/test_structs.py
index fc36d9a..263b917 100644
--- a/hatch_cpp/tests/test_structs.py
+++ b/hatch_cpp/tests/test_structs.py
@@ -46,3 +46,11 @@ def test_cmake_args(self):
         assert f"-DHATCH_CPP_TEST_PROJECT_BASIC_PYTHON_VERSION=3.{version_info.minor}" in hatch_build_plan.commands[0]
         if hatch_build_plan.platform.platform == "darwin":
             assert "-DCMAKE_OSX_DEPLOYMENT_TARGET=11" in hatch_build_plan.commands[0]
+
+    def test_platform_toolchain_override(self):
+        txt = (Path(__file__).parent / "test_project_override_toolchain" / "pyproject.toml").read_text()
+        toml = loads(txt)
+        hatch_build_config = HatchCppBuildConfig(name=toml["project"]["name"], **toml["tool"]["hatch"]["build"]["hooks"]["hatch-cpp"])
+        assert "clang" in hatch_build_config.platform.cc
+        assert "clang++" in hatch_build_config.platform.cxx
+        assert hatch_build_config.platform.toolchain == "gcc"
diff --git a/pyproject.toml b/pyproject.toml
index 6025877..e3b1ee4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -45,6 +45,7 @@ develop = [
     "check-manifest",
     "codespell>=2.4,<2.5",
     "hatchling",
+    "hatch-build",
     "mdformat>=0.7.22,<0.8",
     "mdformat-tables>=1",
     "pytest",