diff --git a/.github/workflows/cicd.yml b/.github/workflows/cicd.yml
index 3de7dfa57..716bccddc 100644
--- a/.github/workflows/cicd.yml
+++ b/.github/workflows/cicd.yml
@@ -23,7 +23,7 @@ jobs:
     - name: "Prepare: restore caches, install Poetry, set up Python"
       uses: ./.github/actions/prepare
       with:
-        python-version: "3.10"
+        python-version: "3.11"
         poetry-version: ${{ env.POETRY_VERSION }}
     - name: Install Python dev dependencies
       run: |
@@ -47,7 +47,7 @@ jobs:
       id: prepare
       uses: ./.github/actions/prepare
       with:
-        python-version: "3.9"
+        python-version: "3.10"
         poetry-version: ${{ env.POETRY_VERSION }}
     - name: Install Python dependencies
       run: |
@@ -61,7 +61,7 @@ jobs:
     timeout-minutes: 15
     strategy:
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11"]
+        python-version: ["3.9", "3.10", "3.11"]
     name: test on Python ${{ matrix.python-version }}
     steps:
     - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
@@ -79,19 +79,15 @@ jobs:
     - name: Install Python dependencies
       run: |
         # Selectively install the optional dependencies for some Python versions
-        # For Python 3.8:
-        if [[ ${{ matrix.python-version }} == '3.8' ]]; then
-          poetry install -E "nn omikuji yake voikko stwfsa";
-        fi
         # For Python 3.9:
         if [[ ${{ matrix.python-version }} == '3.9' ]]; then
-          poetry install -E "fasttext spacy";
-          # download the small English pretrained spaCy model needed by spacy analyzer
-          poetry run python -m spacy download en_core_web_sm --upgrade-strategy only-if-needed
+          poetry install -E "nn omikuji yake voikko stwfsa";
         fi
         # For Python 3.10:
         if [[ ${{ matrix.python-version }} == '3.10' ]]; then
-          poetry install -E "nn omikuji yake stwfsa";
+          poetry install -E "fasttext spacy";
+          # download the small English pretrained spaCy model needed by spacy analyzer
+          poetry run python -m spacy download en_core_web_sm --upgrade-strategy only-if-needed
         fi
         # For Python 3.11:
         if [[ ${{ matrix.python-version }} == '3.11' ]]; then
@@ -103,7 +99,7 @@ jobs:
     - name: Test with pytest
       run: |
         poetry run pytest --cov=./ --cov-report xml
-        if [[ ${{ matrix.python-version }} == '3.9' ]]; then
+        if [[ ${{ matrix.python-version }} == '3.10' ]]; then
           poetry run pytest --cov=./ --cov-report xml --cov-append -m slow
         fi
     - name: Upload coverage to Codecov
diff --git a/.scrutinizer.yml b/.scrutinizer.yml
index ebf755aa4..095b59f43 100644
--- a/.scrutinizer.yml
+++ b/.scrutinizer.yml
@@ -4,7 +4,7 @@ checks:
     duplicate_code: true
 build:
   environment:
-    python: 3.8.12
+    python: 3.9.17
   dependencies:
     override:
      - pip install .[dev]
diff --git a/README.md b/README.md
index e549a20b9..8bb1bcaa3 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ already functional for many common tasks.
 
 Annif is developed and tested on Linux. If you want to run Annif on Windows or Mac OS, the recommended way is to use Docker (see below) or a Linux virtual machine.
 
-You will need Python 3.8+ to install Annif.
+You will need Python 3.9+ to install Annif.
 
 The recommended way is to install Annif from
 [PyPI](https://pypi.org/project/annif/) into a virtual environment.
diff --git a/annif/backend/yake.py b/annif/backend/yake.py
index 8f7d38c50..2eeef9a9c 100644
--- a/annif/backend/yake.py
+++ b/annif/backend/yake.py
@@ -51,7 +51,7 @@ def is_trained(self):
 
     @property
     def label_types(self) -> list[URIRef]:
-        if type(self.params["label_types"]) == str:  # Label types set by user
+        if isinstance(self.params["label_types"], str):  # Label types set by user
             label_types = [lt.strip() for lt in self.params["label_types"].split(",")]
             self._validate_label_types(label_types)
         else:
diff --git a/pyproject.toml b/pyproject.toml
index 1aebd8fbb..6a06219b4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -28,7 +28,7 @@ classifiers=[
 ]
 
 [tool.poetry.dependencies]
-python = ">=3.8,<3.12"
+python = ">=3.9,<3.12"
 
 connexion = {version = "2.14.2", extras = ["swagger-ui"]}
 flask = "2.2.*"
@@ -52,7 +52,6 @@ jsonschema = "4.17.*"
 fasttext-wheel = {version = "0.9.2", optional = true}
 voikko = {version = "0.5.*", optional = true}
 tensorflow-cpu = {version = "2.13.*", optional = true}
-tensorflow-io-gcs-filesystem = {version = "<=0.34.*", optional = true, python = "3.8"}
 lmdb = {version = "1.4.1", optional = true}
 omikuji = {version = "0.5.*", optional = true}
 yake = {version = "0.4.5", optional = true}
@@ -75,7 +74,7 @@ schemathesis = "3.*.*"
 [tool.poetry.extras]
 fasttext = ["fasttext-wheel"]
 voikko = ["voikko"]
-nn = ["tensorflow-cpu", "tensorflow-io-gcs-filesystem", "lmdb"]
+nn = ["tensorflow-cpu", "lmdb"]
 omikuji = ["omikuji"]
 yake = ["yake"]
 spacy = ["spacy"]