diff --git a/.github/workflows/opam-ci.yml b/.github/workflows/opam-ci.yml
index f0ebe912d..5867bcf23 100644
--- a/.github/workflows/opam-ci.yml
+++ b/.github/workflows/opam-ci.yml
@@ -52,7 +52,7 @@ jobs:
         uses: actions/cache/restore@v4
         with:
           path: ~/.opam
-          key: v0.0.1-opam-${{ matrix.setup.os }}-${{ matrix.setup.ocaml-compiler }}-${{ hashFiles('*.opam') }}
+          key: v0.0.2-opam-${{ matrix.setup.os }}-${{ matrix.setup.ocaml-compiler }}-${{ hashFiles('*.opam') }}
 
       - name: Load opam cache when Windows
         if: runner.os == 'Windows'
@@ -60,7 +60,12 @@ jobs:
         uses: actions/cache/restore@v4
         with:
           path: _opam
-          key: v0.0.1-opam-${{ matrix.setup.os }}-${{ matrix.setup.ocaml-compiler }}-${{ hashFiles('**.opam') }}
+          key: v0.0.2-opam-${{ matrix.setup.os }}-${{ matrix.setup.ocaml-compiler }}-${{ hashFiles('**.opam') }}
+
+      - name: Pin lambda-term to fix Windows segfault
+        if: runner.os == 'Windows'
+        run: |
+          opam pin add lambda-term git+https://github.com/davesnx/lambda-term.git#fix-windows-console-segfault -y
 
       - name: Install dependencies
         run: opam install . --deps-only
@@ -88,12 +93,12 @@ jobs:
         if: steps.opam-cache.outputs.cache-hit != 'true' && runner.os != 'Windows'
         with:
           path: ~/.opam
-          key: v0.0.1-opam-${{ matrix.setup.os }}-${{ matrix.setup.ocaml-compiler }}-${{ hashFiles('**.opam') }}
+          key: v0.0.2-opam-${{ matrix.setup.os }}-${{ matrix.setup.ocaml-compiler }}-${{ hashFiles('**.opam') }}
 
       - name: Save cache when Windows
         uses: actions/cache/save@v4
         if: steps.opam-cache-windows.outputs.cache-hit != 'true' && runner.os == 'Windows'
         with:
           path: _opam
-          key: v0.0.1-opam-${{ matrix.setup.os }}-${{ matrix.setup.ocaml-compiler }}-${{ hashFiles('**.opam') }}
+          key: v0.0.2-opam-${{ matrix.setup.os }}-${{ matrix.setup.ocaml-compiler }}-${{ hashFiles('**.opam') }}
 
diff --git a/test/dune b/test/dune
index 418b8bf80..136a09783 100644
--- a/test/dune
+++ b/test/dune
@@ -12,12 +12,17 @@
   ./lib/outcometreePrinter.exe
   ./lib/fdLeak.exe))
 
-; rtopIntegration is disabled on Windows due to a segfault in lambda-term's
-; Windows C stubs when stdout is not a real console handle (ConPTY issue).
+; rtopIntegration on Windows requires lambda-term with the ConPTY segfault fix.
 ; See: https://github.com/ocaml-community/lambda-term/pull/125
-; Re-enable on Windows once lambda-term ships the fix.
+; On Windows, only enabled for OCaml >= 5.0 (opam-ci pins the fixed lambda-term).
+; esy-ci uses 4.14 so the test is naturally skipped there.
 (cram
  (applies_to rtopIntegration)
  (package rtop)
- (enabled_if (= %{os_type} Unix))
+ (enabled_if
+  (or
+   (= %{os_type} Unix)
+   (and
+    (= %{os_type} Win32)
+    (>= %{ocaml_version} 5.0.0))))
  (deps %{bin:ocamlc} %{bin:rtop}))