diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 8fab45c68..2a54bd2e7 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -41,26 +41,33 @@ jobs:
           - "3.11"
           - "3.12"
         openeye: ["no"]
-        gufe-version: ['main']
+        gufe-version: ['a9b5982471eb3644ca8c4423c7001e6309a3f544']
         include:
           - os: "macos-latest"
             python-version: "3.12"
             pydantic-version: ">1"
-            gufe-version: 'main'
+            gufe-version: 'a9b5982471eb3644ca8c4423c7001e6309a3f544'
           - os: "ubuntu-latest"
             python-version: "3.11"
             pydantic-version: "<2"
-            gufe-version: 'main'
+            gufe-version: 'a9b5982471eb3644ca8c4423c7001e6309a3f544'
           - os: "ubuntu-latest"
             python-version: "3.11"
             pydantic-version: ">1"
             openeye: "yes"
-            gufe-version: 'main'
+            gufe-version: 'a9b5982471eb3644ca8c4423c7001e6309a3f544'
           - os: "macos-latest"
             python-version: "3.12"
             pydantic-version: ">1"
             omff-version: ">0.13"
             openeye: ["no"]
+            gufe-version: 'a9b5982471eb3644ca8c4423c7001e6309a3f544'
+
+          # temporary test against gufe main while we're pinned to a9b5
+          - os: "ubuntu-latest"
+            python-version: "3.11"
+            pydantic-version: ">1"
+            openeye: "yes"
             gufe-version: 'main'
 
     env:
diff --git a/environment.yml b/environment.yml
index 01b758334..259518f60 100644
--- a/environment.yml
+++ b/environment.yml
@@ -44,4 +44,4 @@ dependencies:
   - pip:
     - sphinx-toolbox
     - openff-nagl-models>=0.1.2
-    - git+https://github.com/OpenFreeEnergy/gufe@main
\ No newline at end of file
+    - git+https://github.com/OpenFreeEnergy/gufe@main