diff --git a/.circleci/config.yml b/.circleci/config.yml
index 38534393ac..9e4b9ea4ba 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1,13 +1,13 @@
 version: 2.1
 
-orbs:
-  python: circleci/python@1.4.0
-
 executors:
   zenith-build-executor:
     resource_class: xlarge
     docker:
       - image: cimg/rust:1.55.0
+  zenith-python-executor:
+    docker:
+      - image: cimg/python:3.7.10  # Oldest available 3.7 with Ubuntu 20.04 (for GLIBC and Rust) at CirlceCI
 
 jobs:
   check-codestyle:
@@ -183,15 +183,13 @@ jobs:
             - "*"
 
   check-python:
-    executor: python/default
+    executor: zenith-python-executor
     steps:
       - checkout
       - run:
-          name: Install pipenv & deps
+          name: Install deps
           working_directory: test_runner
-          command: |
-            pip install pipenv
-            pipenv install --dev
+          command: pipenv --python 3.7 install --dev
       - run:
           name: Run yapf to ensure code format
           when: always
@@ -204,8 +202,7 @@ jobs:
           command: pipenv run mypy .
 
   run-pytest:
-    #description: "Run pytest"
-    executor: python/default
+    executor: zenith-python-executor
     parameters:
       # pytest args to specify the tests to run.
       #
@@ -240,11 +237,9 @@ jobs:
           steps:
             - run: git submodule update --init --depth 1
       - run:
-          name: Install pipenv & deps
+          name: Install deps
           working_directory: test_runner
-          command: |
-            pip install pipenv
-            pipenv install
+          command: pipenv --python 3.7 install
       - run:
           name: Run pytest
           working_directory: test_runner
diff --git a/README.md b/README.md
index 977d015bfc..3d4392fe9d 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,7 @@ libssl-dev clang pkg-config libpq-dev
 To run the `psql` client, install the `postgresql-client` package or modify `PATH` and `LD_LIBRARY_PATH` to include `tmp_install/bin` and `tmp_install/lib`, respectively.
 
 To run the integration tests (not required to use the code), install
-Python (3.6 or higher), and install python3 packages with `pipenv` using `pipenv install` in the project directory.
+Python (3.7 or higher), and install python3 packages with `pipenv` using `pipenv install` in the project directory.
 
 2. Build zenith and patched postgres
 ```sh
diff --git a/test_runner/Pipfile b/test_runner/Pipfile
index 246a3d419f..e179553dbd 100644
--- a/test_runner/Pipfile
+++ b/test_runner/Pipfile
@@ -19,10 +19,11 @@ cached-property = "*"
 yapf = "==0.31.0"
 mypy = "==0.910"
 # Non-pinned packages follow.
+pipenv = "*"
 flake8 = "*"
 types-requests = "*"
 types-psycopg2 = "*"
 
 [requires]
-# we need at least 3.6, but pipenv doesn't allow to say this directly
+# we need at least 3.7, but pipenv doesn't allow to say this directly
 python_version = "3"
diff --git a/test_runner/Pipfile.lock b/test_runner/Pipfile.lock
index 289639a2ee..185b91189b 100644
--- a/test_runner/Pipfile.lock
+++ b/test_runner/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "48eef51e8eb3c7f0d7284879dd68a83d9b0d9dc835f7a3ff0452b4ddfe9c560a"
+            "sha256": "63b72760ef37375186a638066ba0ad5804dbace99ddc503ea654e9749070ab24"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -162,6 +162,14 @@
             "markers": "python_version >= '3'",
             "version": "==3.3"
         },
+        "importlib-metadata": {
+            "hashes": [
+                "sha256:b618b6d2d5ffa2f16add5697cf57a46c76a56229b0ed1c438322e4e95645bd15",
+                "sha256:f284b3e11256ad1e5d03ab86bb2ccd6f5339688ff17a4d797a0fe7df326f23b1"
+            ],
+            "markers": "python_version < '3.8'",
+            "version": "==4.8.1"
+        },
         "iniconfig": {
             "hashes": [
                 "sha256:011e24c64b7f47f6ebd835bb12a743f2fbe9a26d4cecaa7f53bc4f35ee9da8b3",
@@ -291,9 +299,47 @@
             ],
             "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3, 3.4' and python_version < '4'",
             "version": "==1.26.7"
+        },
+        "zipp": {
+            "hashes": [
+                "sha256:71c644c5369f4a6e07636f0aa966270449561fcea2e3d6747b8d23efaa9d7832",
+                "sha256:9fe5ea21568a0a70e50f273397638d39b03353731e6cbbb3fd8502a33fec40bc"
+            ],
+            "markers": "python_version >= '3.6'",
+            "version": "==3.6.0"
         }
     },
     "develop": {
+        "backports.entry-points-selectable": {
+            "hashes": [
+                "sha256:988468260ec1c196dab6ae1149260e2f5472c9110334e5d51adcb77867361f6a",
+                "sha256:a6d9a871cde5e15b4c4a53e3d43ba890cc6861ec1332c9c2428c92f977192acc"
+            ],
+            "markers": "python_version >= '2.7'",
+            "version": "==1.1.0"
+        },
+        "certifi": {
+            "hashes": [
+                "sha256:78884e7c1d4b00ce3cea67b44566851c4343c120abd683433ce934a68ea58872",
+                "sha256:d62a0163eb4c2344ac042ab2bdf75399a71a2d8c7d47eac2e2ee91b9d6339569"
+            ],
+            "version": "==2021.10.8"
+        },
+        "distlib": {
+            "hashes": [
+                "sha256:c8b54e8454e5bf6237cc84c20e8264c3e991e824ef27e8f1e81049867d861e31",
+                "sha256:d982d0751ff6eaaab5e2ec8e691d949ee80eddf01a62eaa96ddb11531fe16b05"
+            ],
+            "version": "==0.3.3"
+        },
+        "filelock": {
+            "hashes": [
+                "sha256:2b5eb3589e7fdda14599e7eb1a50e09b4cc14f34ed98b8ba56d33bfaafcbef2f",
+                "sha256:34a9f35f95c441e7b38209775d6e0337f9a3759f3565f6c5798f19618527c76f"
+            ],
+            "markers": "python_version >= '3.6'",
+            "version": "==3.3.1"
+        },
         "flake8": {
             "hashes": [
                 "sha256:479b1304f72536a55948cb40a32dce8bb0ffe3501e26eaf292c7e60eb5e0428d",
@@ -302,6 +348,14 @@
             "index": "pypi",
             "version": "==4.0.1"
         },
+        "importlib-metadata": {
+            "hashes": [
+                "sha256:b618b6d2d5ffa2f16add5697cf57a46c76a56229b0ed1c438322e4e95645bd15",
+                "sha256:f284b3e11256ad1e5d03ab86bb2ccd6f5339688ff17a4d797a0fe7df326f23b1"
+            ],
+            "markers": "python_version < '3.8'",
+            "version": "==4.8.1"
+        },
         "mccabe": {
             "hashes": [
                 "sha256:ab8a6258860da4b6677da4bd2fe5dc2c659cff31b3ee4f7f5d64e79735b80d42",
@@ -345,6 +399,22 @@
             ],
             "version": "==0.4.3"
         },
+        "pipenv": {
+            "hashes": [
+                "sha256:05958fadcd70b2de6a27542fcd2bd72dd5c59c6d35307fdac3e06361fb06e30e",
+                "sha256:d180f5be4775c552fd5e69ae18a9d6099d9dafb462efe54f11c72cb5f4d5e977"
+            ],
+            "index": "pypi",
+            "version": "==2021.5.29"
+        },
+        "platformdirs": {
+            "hashes": [
+                "sha256:367a5e80b3d04d2428ffa76d33f124cf11e8fff2acdaa9b43d545f5c7d661ef2",
+                "sha256:8868bbe3c3c80d42f20156f22e7131d2fb321f5bc86a2a345375c6481a67021d"
+            ],
+            "markers": "python_version >= '3.6'",
+            "version": "==2.4.0"
+        },
         "pycodestyle": {
             "hashes": [
                 "sha256:720f8b39dde8b293825e7ff02c475f3077124006db4f440dcbc9a20b76548a20",
@@ -361,6 +431,14 @@
             "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.4.0"
         },
+        "six": {
+            "hashes": [
+                "sha256:1e61c37477a1626458e36f7b1d82aa5c9b094fa4802892072e49de9c60c4c926",
+                "sha256:8abb2f1d86890a2dfb989f9a77cfcfd3e47c2a354b01111771326f8aa26e0254"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==1.16.0"
+        },
         "toml": {
             "hashes": [
                 "sha256:806143ae5bfb6a3c6e736a764057db0e6a0e05e338b5630894a5f779cabb4f9b",
@@ -369,6 +447,42 @@
             "markers": "python_version >= '2.6' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==0.10.2"
         },
+        "typed-ast": {
+            "hashes": [
+                "sha256:01ae5f73431d21eead5015997ab41afa53aa1fbe252f9da060be5dad2c730ace",
+                "sha256:067a74454df670dcaa4e59349a2e5c81e567d8d65458d480a5b3dfecec08c5ff",
+                "sha256:0fb71b8c643187d7492c1f8352f2c15b4c4af3f6338f21681d3681b3dc31a266",
+                "sha256:1b3ead4a96c9101bef08f9f7d1217c096f31667617b58de957f690c92378b528",
+                "sha256:2068531575a125b87a41802130fa7e29f26c09a2833fea68d9a40cf33902eba6",
+                "sha256:209596a4ec71d990d71d5e0d312ac935d86930e6eecff6ccc7007fe54d703808",
+                "sha256:2c726c276d09fc5c414693a2de063f521052d9ea7c240ce553316f70656c84d4",
+                "sha256:398e44cd480f4d2b7ee8d98385ca104e35c81525dd98c519acff1b79bdaac363",
+                "sha256:52b1eb8c83f178ab787f3a4283f68258525f8d70f778a2f6dd54d3b5e5fb4341",
+                "sha256:5feca99c17af94057417d744607b82dd0a664fd5e4ca98061480fd8b14b18d04",
+                "sha256:7538e495704e2ccda9b234b82423a4038f324f3a10c43bc088a1636180f11a41",
+                "sha256:760ad187b1041a154f0e4d0f6aae3e40fdb51d6de16e5c99aedadd9246450e9e",
+                "sha256:777a26c84bea6cd934422ac2e3b78863a37017618b6e5c08f92ef69853e765d3",
+                "sha256:95431a26309a21874005845c21118c83991c63ea800dd44843e42a916aec5899",
+                "sha256:9ad2c92ec681e02baf81fdfa056fe0d818645efa9af1f1cd5fd6f1bd2bdfd805",
+                "sha256:9c6d1a54552b5330bc657b7ef0eae25d00ba7ffe85d9ea8ae6540d2197a3788c",
+                "sha256:aee0c1256be6c07bd3e1263ff920c325b59849dc95392a05f258bb9b259cf39c",
+                "sha256:af3d4a73793725138d6b334d9d247ce7e5f084d96284ed23f22ee626a7b88e39",
+                "sha256:b36b4f3920103a25e1d5d024d155c504080959582b928e91cb608a65c3a49e1a",
+                "sha256:b9574c6f03f685070d859e75c7f9eeca02d6933273b5e69572e5ff9d5e3931c3",
+                "sha256:bff6ad71c81b3bba8fa35f0f1921fb24ff4476235a6e94a26ada2e54370e6da7",
+                "sha256:c190f0899e9f9f8b6b7863debfb739abcb21a5c054f911ca3596d12b8a4c4c7f",
+                "sha256:c907f561b1e83e93fad565bac5ba9c22d96a54e7ea0267c708bffe863cbe4075",
+                "sha256:cae53c389825d3b46fb37538441f75d6aecc4174f615d048321b716df2757fb0",
+                "sha256:dd4a21253f42b8d2b48410cb31fe501d32f8b9fbeb1f55063ad102fe9c425e40",
+                "sha256:dde816ca9dac1d9c01dd504ea5967821606f02e510438120091b84e852367428",
+                "sha256:f2362f3cb0f3172c42938946dbc5b7843c2a28aec307c49100c8b38764eb6927",
+                "sha256:f328adcfebed9f11301eaedfa48e15bdece9b519fb27e6a8c01aa52a17ec31b3",
+                "sha256:f8afcf15cc511ada719a88e013cec87c11aff7b91f019295eb4530f96fe5ef2f",
+                "sha256:fb1bbeac803adea29cedd70781399c99138358c26d05fcbd23c13016b7f5ec65"
+            ],
+            "markers": "python_version < '3.8'",
+            "version": "==1.4.3"
+        },
         "types-psycopg2": {
             "hashes": [
                 "sha256:77ed80f2668582654623e04fb3d741ecce93effcc39c929d7e02f4a917a538ce",
@@ -394,6 +508,22 @@
             "index": "pypi",
             "version": "==3.10.0.2"
         },
+        "virtualenv": {
+            "hashes": [
+                "sha256:10062e34c204b5e4ec5f62e6ef2473f8ba76513a9a617e873f1f8fb4a519d300",
+                "sha256:bcc17f0b3a29670dd777d6f0755a4c04f28815395bca279cdcb213b97199a6b8"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3, 3.4'",
+            "version": "==20.8.1"
+        },
+        "virtualenv-clone": {
+            "hashes": [
+                "sha256:418ee935c36152f8f153c79824bb93eaf6f0f7984bae31d3f48f350b9183501a",
+                "sha256:44d5263bceed0bac3e1424d64f798095233b64def1c5689afa43dc3223caf5b0"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==0.5.7"
+        },
         "yapf": {
             "hashes": [
                 "sha256:408fb9a2b254c302f49db83c59f9aa0b4b0fd0ec25be3a5c51181327922ff63d",
@@ -401,6 +531,14 @@
             ],
             "index": "pypi",
             "version": "==0.31.0"
+        },
+        "zipp": {
+            "hashes": [
+                "sha256:71c644c5369f4a6e07636f0aa966270449561fcea2e3d6747b8d23efaa9d7832",
+                "sha256:9fe5ea21568a0a70e50f273397638d39b03353731e6cbbb3fd8502a33fec40bc"
+            ],
+            "markers": "python_version >= '3.6'",
+            "version": "==3.6.0"
         }
     }
 }
diff --git a/test_runner/README.md b/test_runner/README.md
index fe37fdbcb2..4d42bbd914 100644
--- a/test_runner/README.md
+++ b/test_runner/README.md
@@ -3,10 +3,13 @@
 This directory contains integration tests.
 
 Prerequisites:
-- Python 3.6 or later
+- Python 3.7 or later
+    - Development headers may also be needed to build `psycopg2` from source.
+    - Python 3.7 is recommended if you want to update tests.
 - Dependencies: install them via `pipenv install`. Note that Debian/Ubuntu
   packages are stale, as it commonly happens, so manual installation is not
   recommended.
+  Exact version of `pipenv` is not important unless you change dependencies.
   Run `pipenv shell` to activate the venv or use `pipenv run` to run a single
   command in the venv, e.g. `pipenv run pytest`.
 - Zenith and Postgres binaries
@@ -93,18 +96,48 @@ Cleanup will happen even if the test fails (raises an unhandled exception).
 Python destructors, e.g. `__del__()` aren't recommended for cleanup.
 
 
-### Code quality
+### Before submitting a patch
+#### Obligatory checks
+Install dev dependencies via `pipenv --python 3.7 install --dev` (better)
+or `pipenv install --dev` (if you don't have Python 3.7 and don't need to change dependencies).
 
-We force code formatting via yapf and type hints via mypy:
+We force code formatting via yapf and type hints via mypy.
+Run the following commands in the `test_runner/` directory:
 
-1. Install `yapf` and other tools (`flake8`, `mypy`) with `pipenv install --dev`.
-1. Reformat all your code by running `pipenv run yapf -ri .` in the `test_runner/` directory.
-1. Ensure there are no type errors by running `pipenv run mypy .` in the `test_runner/` directory.
-
-Before submitting a patch, please consider:
+```bash
+pipenv run yapf -ri .  # All code is reformatted
+pipenv run mypy .  # Ensure there are no typing errors
+```
 
+#### Advisable actions
 * Writing a couple of docstrings to clarify the reasoning behind a new test.
 * Running `flake8` (or a linter of your choice, e.g. `pycodestyle`) and fixing possible defects, if any.
 * Adding more type hints to your code to avoid `Any`, especially:
   * For fixture parameters, they are not automatically deduced.
   * For function arguments and return values.
+
+#### Changing dependencies
+You have to update `Pipfile.lock` if you have changed `Pipfile`:
+
+```bash
+pipenv --python 3.7 install --dev  # Re-create venv for Python 3.7 and install recent pipenv inside
+pipenv run pipenv --version  # Should be at least 2021.5.29
+pipenv run pipenv lock  # Regenerate Pipfile.lock
+```
+
+As the minimal supported version is Python 3.7 and we use it in CI,
+you have to use a Python 3.7 environment when updating `Pipfile.lock`.
+Otherwise some back-compatibility packages will be missing.
+
+It is also important to run recent `pipenv`.
+Older versions remove markers from `Pipfile.lock`.
+
+If you don't have Python 3.7, you should install it and its headers (for `psycopg2`)
+separately, e.g.:
+
+```bash
+# In Ubuntu
+sudo add-apt-repository ppa:deadsnakes/ppa
+sudo apt update
+sudo apt install python3.7 python3.7-dev
+```