diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 089d185..1184b36 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -18,6 +18,7 @@ jobs:
         php:
           - 8.2
           - 8.3
+          - 8.4
 
     steps:
       - name: Set up PHP
@@ -28,7 +29,7 @@ jobs:
           ini-values: zend.assertions=1
 
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Validate composer.json and composer.lock
         run: composer validate --strict
@@ -47,23 +48,3 @@ jobs:
 
       - name: Run tests
         run: composer test
-
-  psalm:
-    name: Psalm
-    runs-on: ubuntu-latest
-
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v3
-
-      - name: Set up PHP
-        uses: shivammathur/setup-php@v2
-        with:
-          php-version: ${{ matrix.php }}
-          extensions: bcmath, gmp, intl, dom, mbstring
-
-      - name: Download dependencies
-        run: composer install --classmap-authoritative
-
-      - name: Psalm
-        run: vendor/bin/psalm
diff --git a/composer.json b/composer.json
index f0352cb..9877270 100644
--- a/composer.json
+++ b/composer.json
@@ -12,24 +12,19 @@
     ],
     "require": {
         "php": ">=8.2",
-        "symfony/framework-bundle": "^7.1",
-        "symfony/property-access": "^7.1",
-        "symfony/serializer": "^7.1",
-        "symfony/validator": "^7.1",
+        "symfony/framework-bundle": "^7.0",
+        "symfony/property-access": "^7.0",
+        "symfony/serializer": "^7.0",
+        "symfony/validator": "^7.0",
         "zircote/swagger-php": "^4.7",
-        "symfony/expression-language": "^7.1"
+        "symfony/expression-language": "^7.0"
     },
     "require-dev": {
         "roave/security-advisories": "dev-latest",
-        "vimeo/psalm": "^5.0",
         "phpunit/phpunit": "^10.0",
-        "psalm/plugin-phpunit": "^0.18",
-        "symfony/browser-kit": "^7.1",
+        "symfony/browser-kit": "^7.0",
         "friendsofphp/php-cs-fixer": "^3.54"
     },
-    "conflict": {
-        "zircote/swagger-php": "=4.8.7"
-    },
     "autoload": {
         "psr-4": {
             "OpenSolid\\OpenApiBundle\\": "src/"
diff --git a/psalm.xml b/psalm.xml
deleted file mode 100644
index 204c5d7..0000000
--- a/psalm.xml
+++ /dev/null
@@ -1,56 +0,0 @@
-<?xml version="1.0"?>
-<psalm
-    findUnusedPsalmSuppress="true"
-    findUnusedBaselineEntry="false"
-    findUnusedCode="false"
-    findUnusedVariablesAndParams="true"
-    strictBinaryOperands="true"
-    errorLevel="7"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xmlns="https://getpsalm.org/schema/config"
-    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
->
-    <projectFiles>
-        <directory name="src"/>
-        <ignoreFiles>
-            <directory name="vendor"/>
-        </ignoreFiles>
-    </projectFiles>
-
-    <issueHandlers>
-        <UnusedClass>
-            <errorLevel type="suppress">
-                <directory name="src"/>
-            </errorLevel>
-        </UnusedClass>
-        <PossiblyUnusedMethod>
-            <errorLevel type="suppress">
-                <directory name="src"/>
-            </errorLevel>
-        </PossiblyUnusedMethod>
-        <InternalMethod>
-            <errorLevel type="suppress">
-                <directory name="src"/>
-            </errorLevel>
-        </InternalMethod>
-        <PossiblyUnusedProperty>
-            <errorLevel type="suppress">
-                <directory name="src"/>
-            </errorLevel>
-        </PossiblyUnusedProperty>
-        <UndefinedClass>
-            <errorLevel type="suppress">
-                <referencedClass name="IntBackedEnum"/>
-            </errorLevel>
-        </UndefinedClass>
-        <PropertyNotSetInConstructor>
-            <errorLevel type="suppress">
-                <directory name="src"/>
-            </errorLevel>
-        </PropertyNotSetInConstructor>
-    </issueHandlers>
-
-    <plugins>
-        <pluginClass class="Psalm\PhpUnitPlugin\Plugin"/>
-    </plugins>
-</psalm>