diff --git a/Makefile b/Makefile
index af982516..e9ed6dfe 100644
--- a/Makefile
+++ b/Makefile
@@ -58,11 +58,11 @@ zephyr-setup: fprime-venv ## Set up Zephyr environment
 
 .PHONY: pre-commit-install
 pre-commit-install: uv ## Install pre-commit hooks
-	@$(UVX) pre-commit install > /dev/null
+	@$(UVX_PINNED) pre-commit install > /dev/null
 
 .PHONY: fmt
 fmt: pre-commit-install ## Lint and format files
-	@$(UVX) pre-commit run --all-files
+	@$(UVX_PINNED) pre-commit run --all-files
 
 .PHONY: data-budget
 data-budget: fprime-venv ## Analyze telemetry data budget (use VERBOSE=1 for detailed output)
diff --git a/makelib/build-tools.mk b/makelib/build-tools.mk
index 9e346c8f..f2dfb4d1 100644
--- a/makelib/build-tools.mk
+++ b/makelib/build-tools.mk
@@ -10,10 +10,19 @@ $(TOOLS_DIR):
 ### Tool Versions
 UV_VERSION ?= 0.8.13
 
+### Python version used for tooling environments. Single source of truth is .python-version, so
+### that tools do not silently build against whichever interpreter happens to be on the machine.
+PYTHON_VERSION ?= $(shell cat .python-version)
+
 ### uv & uvx
 UV_DIR ?= $(TOOLS_DIR)/uv-$(UV_VERSION)
 UV ?= $(UV_DIR)/uv
 UVX ?= $(UV_DIR)/uvx
+### Pin the interpreter for uvx-run tooling. pre-commit builds its hook environments with whatever
+### Python runs it, so without this a machine defaulting to an older interpreter builds hook
+### environments that cannot parse project sources written for .python-version. uv downloads the
+### pinned interpreter if it is missing.
+UVX_PINNED ?= $(UVX) --python $(PYTHON_VERSION)
 .PHONY: uv
 uv: $(UV) ## Download uv
 $(UV): $(TOOLS_DIR)