diff --git a/.github/workflows/black.yml b/.github/workflows/black.yml
index 15791da38..c0e16a6c9 100644
--- a/.github/workflows/black.yml
+++ b/.github/workflows/black.yml
@@ -17,7 +17,7 @@ jobs:
     - uses: actions/checkout@v4
     - uses: actions/setup-python@v5
       with:
-        python-version: 3.7
+        python-version: 3.8
         cache: 'pip'
         cache-dependency-path: '.github/workflows/black.yml'
     - run: pip install black==22.3.0
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index df540aed4..b4b2f4568 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -92,7 +92,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version:
-          - 3.7
+          - 3.8
         action:
           - TEST=Dataset
           - TEST=fork_exec
@@ -158,7 +158,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version:
-          - 3.7
+          - 3.8
         tf-version:
           - 2.10.0
         action:
@@ -175,22 +175,22 @@ jobs:
           - TEST=tools
         include:
           - action: TEST=TFUtil
-            python-version: 3.7
+            python-version: 3.8
             tf-version: 1.15.3
           - action: TEST=TFEngine
-            python-version: 3.7
+            python-version: 3.8
             tf-version: 1.15.3
           - action: TEST=TFEngine
-            python-version: 3.7
+            python-version: 3.8
             tf-version: 2.3.0
           - action: TEST=TFNativeOp
-            python-version: 3.7
+            python-version: 3.8
             tf-version: 1.14.0
           - action: TEST=TFNetworkSigProcLayer
-            python-version: 3.7
+            python-version: 3.8
             tf-version: 1.15.3
           - action: TEST=demos RETURNN_DISABLE_TORCH=1
-            python-version: 3.7
+            python-version: 3.8
             tf-version: 2.3.0
 
     steps:
@@ -358,7 +358,7 @@ jobs:
         include:
           # Some selected tests (but not all) with some other versions.
           - action: TEST=rf_base
-            python-version: 3.7
+            python-version: 3.8
             torch-version: 1.13.1
             tf-version: 2.10.0
 
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 439117a59..f144bb229 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -26,7 +26,7 @@ jobs:
 
     - uses: actions/setup-python@v5
       with:
-        python-version: 3.7
+        python-version: 3.8
 
     - name: Install Python deps
       run: |
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c312078f8..557467a89 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,8 @@ or any changes which could potentially break or change the behavior of existing
 This is intentionally kept short. For a full change log, just see the Git log.
 
 
+## 2023-12-13: Bump min Python version from 3.7 to 3.8 ([issue #1326](https://github.com/rwth-i6/returnn/issues/1326))
+
 ## 2024-06-07: `VariableDataset`
 
 Custom subdataset per subepoch based on user-provided function.
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index b9699abca..f9936e237 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -29,7 +29,7 @@ General rules when contributing to the code of RETURNN:
   and in general to use newer TF features (even maybe TF >=2),
   as long as your new feature (new layer or so) is just optional.
   For older TF support, `TFCompat.py` might be helpful. (See code for examples.)
-* We support Python >=3.7 ([discussion](https://github.com/rwth-i6/returnn/issues/487)).
+* We support Python >=3.8 ([discussion](https://github.com/rwth-i6/returnn/issues/1326)).
 
 About new features:
 
diff --git a/pyproject.toml b/pyproject.toml
index a14bd4aae..14c8c02ca 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.black]
 line-length = 120
-target-version = ["py37"]  # https://github.com/rwth-i6/returnn/issues/487
+target-version = ["py38"]  # https://github.com/rwth-i6/returnn/issues/1326
 extend-exclude = '''
 /(
     # All Git submodules, see .gitmodules.
diff --git a/tests/PyCharm.idea/inspectionProfiles/Project_Default.xml b/tests/PyCharm.idea/inspectionProfiles/Project_Default.xml
index 88cda7840..6be6cae45 100644
--- a/tests/PyCharm.idea/inspectionProfiles/Project_Default.xml
+++ b/tests/PyCharm.idea/inspectionProfiles/Project_Default.xml
@@ -4,10 +4,9 @@
     <inspection_tool class="PyCompatibilityInspection" enabled="true" level="WARNING" enabled_by_default="true">
       <option name="ourVersions">
         <value>
-          <list size="3">
-            <item index="0" class="java.lang.String" itemvalue="3.7" />
-            <item index="1" class="java.lang.String" itemvalue="3.8" />
-            <item index="2" class="java.lang.String" itemvalue="3.9" />
+          <list size="2">
+            <item index="0" class="java.lang.String" itemvalue="3.8" />
+            <item index="1" class="java.lang.String" itemvalue="3.9" />
           </list>
         </value>
       </option>