diff --git a/.github/workflows/tests-ubuntu.yml b/.github/workflows/tests-ubuntu.yml
index a34112698..a193ca05f 100644
--- a/.github/workflows/tests-ubuntu.yml
+++ b/.github/workflows/tests-ubuntu.yml
@@ -37,7 +37,8 @@ jobs:
         - python-version: "3.13"
           env:
             TOXENV: no-reactor
-        - python-version: pypy3.11
+        # pinned due to https://github.com/pypy/pypy/issues/5388
+        - python-version: pypy3.11-7.3.20
           env:
             TOXENV: pypy3
 
@@ -51,7 +52,8 @@ jobs:
         - python-version: "3.10.19"
           env:
             TOXENV: no-reactor-pinned
-        - python-version: pypy3.11
+        # pinned due to https://github.com/pypy/pypy/issues/5388
+        - python-version: pypy3.11-7.3.20
           env:
             TOXENV: pypy3-pinned
         - python-version: "3.10.19"
@@ -67,7 +69,8 @@ jobs:
         - python-version: "3.13"
           env:
             TOXENV: no-reactor-extra-deps
-        - python-version: pypy3.11
+        # pinned due to https://github.com/pypy/pypy/issues/5388
+        - python-version: pypy3.11-7.3.20
           env:
             TOXENV: pypy3-extra-deps
         - python-version: "3.13"
diff --git a/tox.ini b/tox.ini
index ca304330c..d35b0406c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -288,6 +288,8 @@ basepython = {[pinned]basepython}
 deps =
     {[pinned]deps}
     botocore==1.13.45
+    # botocore 1.13.45 requires urllib3>=1.20,<1.26; requests 2.33.0 requires urllib3>=1.26,<3
+    requests<2.33.0
 setenv =
     {[pinned]setenv}
 commands =