diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a74996e..ef1a078 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -63,7 +63,17 @@ jobs:
           version: ${{ matrix.version }}
       - uses: julia-actions/cache@v1
       - name: "Instantiate test environment"
-        run: julia --project=test devrepl.jl
+        shell: julia --project=test {0}
+        run: |
+          import Pkg
+          Pkg.develop(path=pwd())
+          # Pin the lowest version of all dependencies that we've declared compatible
+          Pkg.pin(name="AbstractTrees", version="0.4.0")
+          Pkg.pin(name="Bibliography", version="0.2.0")
+          Pkg.pin(name="Documenter", version="1.0.0")
+          Pkg.pin(name="MarkdownAST", version="0.1.2")
+          Pkg.pin(name="OrderedCollections", version="1.6.0")
+          Pkg.status()
       - name: "Run tests"
         shell: julia --color=yes --project=test --depwarn="yes" --check-bounds="yes" {0}
         run: |
diff --git a/Project.toml b/Project.toml
index 8d6729c..dd1465e 100644
--- a/Project.toml
+++ b/Project.toml
@@ -17,5 +17,5 @@ AbstractTrees = "^0.4"
 Bibliography = "^0.2"
 Documenter = "1"
 MarkdownAST = "0.1.2"
-OrderedCollections = "1"
+OrderedCollections = "1.6"
 julia = "^1.6"