diff --git a/Makefile b/Makefile
index d1d306f9..36a14632 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,4 @@
+# Find an extensive introduction to Makefiles here: https://makefiletutorial.com/
 
 # Use bash as the shell when executing a rule's recipe. For more details:
 # https://www.gnu.org/software/make/manual/html_node/Choosing-the-Shell.html
@@ -7,6 +8,11 @@ SHELL := bash
 PACKAGE_NAME := package
 PACKAGE_VERSION := $(shell python -c $$'try: import $(PACKAGE_NAME); print($(PACKAGE_NAME).__version__);\nexcept: print("unknown");')
 
+# Files that this package depends on are in the src/ folder, so collect them
+# all into a list. Also collect everything needed for testing this package.
+PACKAGE_DEPS := $(shell find src/$(PACKAGE_NAME)/ -type f -not -path "*/__pycache__/*")
+PACKAGE_DEPS_TEST := $(shell find tests/ -type f -not -path "*/__pycache__/*")
+
 # This variable contains the first goal that matches any of the listed goals
 # here, else it contains an empty string. The net effect is to filter out
 # whether this current run of `make` requires a Python virtual environment
@@ -106,7 +112,8 @@ upgrade-quiet:
 
 # Generate a Software Bill of Materials (SBOM).
 .PHONY: sbom
-sbom: requirements
+sbom: requirements dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-sbom.json
+dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-sbom.json:
 	cyclonedx-py --force --requirements --format json --output dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-sbom.json
 
 # Generate a requirements.txt file containing version and integrity hashes for all
@@ -119,8 +126,8 @@ sbom: requirements
 # We also want to make sure that this package itself is added to the requirements.txt
 # file, and if possible even with proper hashes.
 .PHONY: requirements
-requirements: requirements.txt
-requirements.txt: pyproject.toml
+requirements: requirements.txt dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-requirements.txt
+requirements.txt dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-requirements.txt: .venv/upgraded-on
 	echo -n "" > requirements.txt
 	for pkg in $$(python -m pip freeze --local --disable-pip-version-check --exclude-editable); do \
 	  pkg=$${pkg//[$$'\r\n']}; \
@@ -162,14 +169,18 @@ check-mypy:
 	pre-commit run mypy --all-files
 check-actionlint:
 	pre-commit run actionlint --all-files
-check:
+check: .venv/checked-on
+.venv/checked-on: $(PACKAGE_DEPS)
 	pre-commit run --all-files
+	echo "Automatically generated by Python Package Makefile on $$(date '+%Y-%m-%d %H:%M:%S %z')." > .venv/checked-on
 
 # Run all unit tests. The --files option avoids stashing but passes files; however,
 # the hook setup itself does not pass files to pytest (see .pre-commit-config.yaml).
 .PHONY: test
-test:
+test: .venv/tested-on
+.venv/tested-on: $(PACKAGE_DEPS) $(PACKAGE_DEPS_TEST)
 	pre-commit run pytest --hook-stage push --files tests/
+	echo "Automatically generated by Python Package Makefile on $$(date '+%Y-%m-%d %H:%M:%S %z')." > .venv/tested-on
 
 # Build a source distribution package and a binary wheel distribution artifact.
 # When building these artifacts, we need the environment variable SOURCE_DATE_EPOCH
@@ -223,6 +234,7 @@ prune:
 .PHONY: dist-clean clean
 dist-clean:
 	rm -fr dist/*
+	rm -f .venv/checked-on .venv/tested-on
 	rm -f requirements.txt
 clean: dist-clean
 	rm -fr .coverage .hypothesis/ .mypy_cache/ .pytest_cache/