diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b2faf7f..59ae727 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -23,6 +23,7 @@ jobs:
         - 'pypy-3.10'
         # this version range needs to be synchronized with the one in pyproject.toml
         amaranth-version:
+        - '0.5'
         - 'git'
         allow-failure:
         - false
@@ -30,11 +31,11 @@ jobs:
     name: 'test (${{ matrix.python-version }}, HDL ${{ matrix.amaranth-version }})'
     steps:
       - name: Check out source code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - name: Set up PDM
-        uses: pdm-project/setup-pdm@v3
+        uses: pdm-project/setup-pdm@v4
         with:
           python-version: ${{ matrix.python-version }}
       - name: Install dependencies
@@ -60,14 +61,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out source code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - name: Fetch tags from upstream repository
         run: |
           git fetch --tags https://github.com/amaranth-lang/amaranth-stdio.git
       - name: Set up PDM
-        uses: pdm-project/setup-pdm@v3
+        uses: pdm-project/setup-pdm@v4
         with:
           python-version: '3.12'
       - name: Install dependencies
@@ -77,7 +78,7 @@ jobs:
         run: |
           pdm run document
       - name: Upload documentation archive
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: docs
           path: docs/_build
@@ -97,11 +98,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out source code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - name: Download documentation archive
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: docs
           path: docs/
@@ -130,11 +131,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out source code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - name: Download documentation archive
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: docs
           path: pages/docs/${{ github.ref_name }}/
diff --git a/pyproject.toml b/pyproject.toml
index bc54867..7b4611e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,7 +14,7 @@ license = {file = "LICENSE.txt"}
 requires-python = "~=3.8"
 dependencies = [
   # this version requirement needs to be synchronized with the one in .github/workflows/main.yml
-  "amaranth @ git+https://github.com/amaranth-lang/amaranth",
+  "amaranth>=0.5,<0.6",
 ]
 
 [project.urls]