diff --git a/.github/workflows/ci-sage.yml b/.github/workflows/ci-sage.yml
index 56ad9a4f..0e174cbd 100644
--- a/.github/workflows/ci-sage.yml
+++ b/.github/workflows/ci-sage.yml
@@ -151,15 +151,17 @@ jobs:
         make -j4 check-all
         make -j4 distcheck
 
-  docker:
-    uses: sagemath/sage/.github/workflows/docker.yml@develop
+  linux:
+    uses: mkoeppe/sage/.github/workflows/docker.yml@tox_2023_09
     with:
       # FIXME: duplicated from env.TARGETS
       targets_pre:       build/make/Makefile
       targets:           SAGE_CHECK=no SAGE_CHECK_PACKAGES="cysignals,cypari" cysignals cypari
       targets_optional:  build/make/Makefile
-      sage_repo:         sagemath/sage
-      sage_ref:          develop
+      sage_repo:         mkoeppe/sage
+      sage_ref:          tox_2023_09
+      #sage_repo:         sagemath/sage
+      #sage_ref:          develop
       upstream_artifact: upstream
       # We prefix the image name with the SPKG name ("cysignals-") to avoid the error
       # 'Package "sage-docker-..." is already associated with another repository.'
@@ -205,13 +207,15 @@ jobs:
       osversion_xcodeversion_toxenv_tuples: >-
         [["latest", "",           "homebrew-macos-usrlocal-minimal"],
          ["latest", "",           "homebrew-macos-usrlocal-standard"],
-         ["13",     "xcode_15.0", ""homebrew-macos-usrlocal-standard"],
+         ["13",     "xcode_15.0", "homebrew-macos-usrlocal-standard"],
          ["latest", "",           "conda-forge-macos-standard"]]
       # FIXME: duplicated from env.TARGETS
       targets_pre:       build/make/Makefile
       targets:           SAGE_CHECK=no SAGE_CHECK_PACKAGES="cysignals,cypari" cysignals cypari
       targets_optional:  build/make/Makefile
-      sage_repo:         sagemath/sage
-      sage_ref:          refs/pull/36110/merge
+      sage_repo:         mkoeppe/sage
+      sage_ref:          tox_2023_09
+      #sage_repo:         sagemath/sage
+      #sage_ref:          refs/pull/36110/merge
       upstream_artifact: upstream
     needs: [dist, macos-without-sage]