diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 3c6a5f91b6..fe677fe258 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -98,7 +98,7 @@ jobs:
         timeout-minutes: 120 # this usually takes 20-45 minutes (or hangs for 6+ hours).
         run: |
           python -c "import julia; julia.install(); import diffeqpy; diffeqpy.install()"
-          julia -e 'using Pkg; Pkg.add(PackageSpec(name="ReactionMechanismSimulator",rev="main")); using ReactionMechanismSimulator'
+          julia -e 'using Pkg; Pkg.add(PackageSpec(name="ReactionMechanismSimulator",rev="marcus_development")); using ReactionMechanismSimulator'
 
       - name: Install Q2DTor
         run: echo "" | make q2dtor