diff --git a/Dockerfile b/Dockerfile
index 760d6ef..7045925 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,8 @@
 ARG PHP_VERSION=8.3
 ARG DEBIAN_VERSION=bookworm
+ARG COMPOSER_VERSION=2.7.6
 
-FROM composer:2.7.1 as composer
+FROM composer:${COMPOSER_VERSION} as composer
 
 FROM php:${PHP_VERSION}-cli-${DEBIAN_VERSION}
 
diff --git a/Makefile b/Makefile
index e0ec19f..6c2d841 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,22 @@
 ARGS_PHPUNIT ?=
 
 DOCKER := $(if $(LRN_SDK_NO_DOCKER),,$(shell which docker))
-PHP_VERSION = 8.3
-DEBIAN_VERSION = bookworm
-IMAGE = php-cli-composer:$(PHP_VERSION)
+
+# PHP Evolution
+SUPPORTED_PHP_VERSIONS = 7.1 7.2 7.3 7.4 8.0 8.1 8.2 8.3
+PHP_VERSION = $(lastword ${SUPPORTED_PHP_VERSIONS})
+DEBIAN_VERSION-7.1 = buster
+DEBIAN_VERSION-7.2 = buster
+DEBIAN_VERSION-7.3 = bullseye
+DEBIAN_VERSION-7.4 = bullseye
+DEBIAN_VERSION-8.0 = bullseye
+DEBIAN_VERSION-def = bookworm
+DEBIAN_VERSION = $(or $(DEBIAN_VERSION-$(PHP_VERSION)),$(DEBIAN_VERSION-def))
+COMPOSER_VERSION-7.1 = 2.2
+COMPOSER_VERSION-def = 2.7.6
+COMPOSER_VERSION = $(or $(COMPOSER_VERSION-$(PHP_VERSION)),$(COMPOSER_VERSION-def))
+
+IMAGE = php-cli-composer:$(PHP_VERSION)-$(DEBIAN_VERSION)-$(COMPOSER_VERSION)
 
 TARGETS = all build devbuild prodbuild \
 	quickstart check-quickstart install-vendor \
@@ -28,8 +41,14 @@ $(TARGETS): $(if $(shell docker image ls -q --filter reference=$(IMAGE)),,docker
 	$(DKR) make -e MAKEFLAGS="$(MAKEFLAGS)" $@
 
 docker-build:
-	docker image build --progress plain --build-arg PHP_VERSION=$(PHP_VERSION) --build-arg DEBIAN_VERSION=$(DEBIAN_VERSION) -t $(IMAGE) .
-.PHONY: docker-build
+	docker image build \
+		--progress plain \
+		--build-arg PHP_VERSION=$(PHP_VERSION) \
+		--build-arg DEBIAN_VERSION=$(DEBIAN_VERSION) \
+		--build-arg COMPOSER_VERSION=$(COMPOSER_VERSION) \
+		-t $(IMAGE) .
+.PHONY: docker-build lrn-test-all lrn-test-clean
+
 
 else
 DIST_PREFIX = learnosity_sdk-
@@ -64,19 +83,19 @@ prodbuild: install-vendor
 release:
 	@./release.sh
 
-lint: install-vendor
+lint: build
 	$(PHPCS) src
 
-test: install-vendor
-	$(PHPUNIT) --do-not-cache-result $(ARGS_PHPUNIT)
+test: build
+	$(PHPUNIT) $(if $(subst 7.1,,$(PHP_TARGET)),--do-not-cache-result) $(ARGS_PHPUNIT)
 
-test-coverage: install-vendor
+test-coverage: build
 	XDEBUG_MODE=coverage $(PHPUNIT) --do-not-cache-result $(ARGS_PHPUNIT)
 
-test-unit: install-vendor
+test-unit: build
 	$(PHPUNIT) --do-not-cache-result --testsuite unit $(ARGS_PHPUNIT)
 
-test-integration-env: install-vendor
+test-integration-env: build
 	$(PHPUNIT) --do-not-cache-result --testsuite integration $(ARGS_PHPUNIT)
 
 ###
@@ -104,8 +123,8 @@ dist-test: dist-zip install-vendor
 ###
 # install vendor rules
 ###
-install-vendor: vendor/autoload.php
-vendor/autoload.php: composer.json
+install-vendor: composer.lock
+composer.lock: composer.json
 	$(COMPOSER) install $(COMPOSER_INSTALL_FLAGS) $(VENDOR_FLAGS)
 
 clean: clean-dist clean-test clean-vendor
diff --git a/src/Services/PreHashStringFactory.php b/src/Services/PreHashStringFactory.php
index b5ae08f..5642e71 100644
--- a/src/Services/PreHashStringFactory.php
+++ b/src/Services/PreHashStringFactory.php
@@ -13,7 +13,10 @@ class PreHashStringFactory
         LegacyPreHashString::class,
     ];
 
-    protected array $validServices;
+    /**
+     * @var array
+     */
+    protected /* array */ $validServices;
 
     public function __construct()
     {
diff --git a/src/Services/PreHashStrings/LegacyPreHashString.php b/src/Services/PreHashStrings/LegacyPreHashString.php
index dd36839..c5d76bd 100644
--- a/src/Services/PreHashStrings/LegacyPreHashString.php
+++ b/src/Services/PreHashStrings/LegacyPreHashString.php
@@ -94,11 +94,15 @@ class LegacyPreHashString implements PreHashStringInterface
         'domain',
     ];
 
-    /** Service name to generate a pre-hash string for */
-    protected string $service;
+    /** Service name to generate a pre-hash string for
+     * @var string
+     */
+    protected /* string */ $service;
 
-    /** V1-compat strings need the secret to be part of the pre-hash string */
-    protected bool $v1Compat;
+    /** V1-compat strings need the secret to be part of the pre-hash string
+     * @var bool
+     */
+    protected /* bool */ $v1Compat;
 
     public function __construct(string $service, bool $v1Compat = false)
     {
diff --git a/tests/Request/InitTest.php b/tests/Request/InitTest.php
index b25cf7c..aaf496a 100644
--- a/tests/Request/InitTest.php
+++ b/tests/Request/InitTest.php
@@ -153,6 +153,9 @@ public function testNullRequestPacketAndActionGeneratesValidInit()
         $this->assertInstanceOf(Init::class, $initObject);
     }
 
+    /**
+     * @requires PHPUnit >= 9.6
+     */
     public function testMetaWithTelemetryOnlyAddsSdkProp()
     {
         list($service, $security, $secret, $request, $action) = ParamsFixture::getWorkingQuestionsApiParams();
@@ -170,6 +173,9 @@ public function testMetaWithTelemetryOnlyAddsSdkProp()
         $this->assertEquals(1, count((array) $generatedObject->meta));
     }
 
+    /**
+     * @requires PHPUnit >= 9.6
+     */
     public function testRequestWithTelemetryPreservesOtherMetaProps()
     {
         list($service, $security, $secret, $request, $action) = ParamsFixture::getWorkingQuestionsApiParams();
@@ -195,6 +201,9 @@ public function testRequestWithTelemetryPreservesOtherMetaProps()
         $this->assertObjectHasProperty('sdk', $generatedObject->meta);
     }
 
+    /**
+     * @requires PHPUnit >= 9.6
+     */
     public function testRequestWithoutTelemetryPreservesEmptyMeta()
     {
         // We disable telemetry to be able to reliably test signature generation. Added telemetry
@@ -210,6 +219,9 @@ public function testRequestWithoutTelemetryPreservesEmptyMeta()
         $this->assertObjectNotHasProperty('meta', $generatedObject);
     }
 
+    /**
+     * @requires PHPUnit >= 9.6
+     */
     public function testRequestWithoutTelemetryPreservesFilledMeta()
     {
         // We disable telemetry to be able to reliably test signature generation. Added telemetry
diff --git a/tests/Services/LegacySignaturesTest.php b/tests/Services/LegacySignaturesTest.php
index e6b1064..0d8ebe3 100644
--- a/tests/Services/LegacySignaturesTest.php
+++ b/tests/Services/LegacySignaturesTest.php
@@ -11,7 +11,10 @@
 
 class LegacySignaturesTest extends AbstractTestCase
 {
-    private SignatureFactory $signatureFactory;
+    /**
+     * @var SignatureFactory
+     */
+    private /* SignatureFactory */ $signatureFactory;
 
     public function setUp(): void
     {