diff --git a/Changelog.md b/Changelog.md
index 5efdd360..c9d19e11 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -14,6 +14,7 @@ All notable changes to this project will be documented here.
 - Disable pytest cacheprovider to avoid creating .pytest_cache in isolated runs (#709)
 - Fixed Python tester to correctly report marks when `markus_marks_earned` equals total or zero (#716)
 - Fix worker orphan processes and add server-side max test timeout cap (#710)
+- Resolve ghcup isolation installation failure in Haskell autotester (#725)
 
 ## [v2.9.0]
 - Install stack with GHCup (#626)
diff --git a/server/autotest_server/testers/haskell/requirements.system b/server/autotest_server/testers/haskell/requirements.system
index 559e854f..48176b85 100755
--- a/server/autotest_server/testers/haskell/requirements.system
+++ b/server/autotest_server/testers/haskell/requirements.system
@@ -21,5 +21,13 @@ if [ ! -x "/usr/local/bin/stack" ]; then
     libgmp10 \
     libncurses-dev
   curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | BOOTSTRAP_HASKELL_NONINTERACTIVE=1 BOOTSTRAP_HASKELL_MINIMAL=1 sh
-  $HOME/.ghcup/bin/ghcup install stack recommended --isolate /usr/local/bin
-fi
+
+  # Create a dedicated, empty folder to satisfy ghcup's isolation requirements
+  mkdir -p /usr/local/bin/stack-isolated
+
+  # Install stack cleanly into the isolated subfolder
+  ~/.ghcup/bin/ghcup install stack recommended --isolate /usr/local/bin/stack-isolated
+
+  # Link the executable back into the global PATH
+  ln -sf /usr/local/bin/stack-isolated/stack /usr/local/bin/stack
+fi
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