diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
index 316f1640..02890fa3 100644
--- a/.github/workflows/haskell-ci.yml
+++ b/.github/workflows/haskell-ci.yml
@@ -292,6 +292,12 @@ jobs:
       - name: prepare for constraint sets
         run: |
           rm -f cabal.project.local
+      - name: constraint set prefer-oldest
+        run: |
+          $CABAL v2-build $ARG_COMPILER --disable-tests --disable-benchmarks --prefer-oldest all --dry-run
+          cabal-plan topo | sort
+          $CABAL v2-build $ARG_COMPILER --disable-tests --disable-benchmarks --prefer-oldest --dependencies-only -j2 all
+          $CABAL v2-build $ARG_COMPILER --disable-tests --disable-benchmarks --prefer-oldest all
       - name: save cache
         if: always()
         uses: actions/cache/save@v4
diff --git a/cabal.haskell-ci b/cabal.haskell-ci
index 4ee70509..262ce117 100644
--- a/cabal.haskell-ci
+++ b/cabal.haskell-ci
@@ -91,21 +91,24 @@ macos-jobs: ==8.10.*
 -- Package will be build with different constraints.
 -- This is useful to check compatibility with older versions of dependencies.
 
-constraint-set deepseq-1.4
-  ghc: (>= 7.8 && <7.10) || == 8.2.2
-  constraints: deepseq ==1.4.*
-  constraints: binary installed
+constraint-set prefer-oldest
+  -- we can limit GHC's and add extra constraints for each constraint-set
+  -- for haskell-ci itself, we don't.
+
+  --  ghc: (>= 7.8 && <7.10) || == 8.2.2
+  --  constraints: deepseq ==1.4.*
 
   -- Constraint sets accept booleans for few steps, as the main script
   -- Defaults are False.
   -- These fields don't accept version ranges: you should rather create
   -- another constraint set.
 
-  -- tests: False
-  -- run-tests: False
+  tests: False
+  run-tests: False
+  prefer-oldest: True
   -- docspec: False
   -- benchmarks: False
-  haddock: True
+  -- haddock: True
 
 -- Copy over additional properties specified in a cabal.project file.
 -- Possible values are:
diff --git a/haskell-ci.cabal b/haskell-ci.cabal
index dee3a955..cea83d90 100644
--- a/haskell-ci.cabal
+++ b/haskell-ci.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.2
 name:               haskell-ci
-version:            0.19.20250506
+version:            0.19.20250531
 synopsis:           Haskell CI script generator
 description:
   Script generator (@haskell-ci@) for
diff --git a/haskell-ci.sh b/haskell-ci.sh
index 6c81e800..7d0a32b1 100755
--- a/haskell-ci.sh
+++ b/haskell-ci.sh
@@ -549,7 +549,9 @@ run_cmd $CABAL v2-build $ARG_COMPILER --disable-tests --disable-benchmarks all
 # constraint sets
 put_info "constraint sets"
 run_cmd rm -f cabal.project.local
-put_info "constraint set deepseq-1.4"
+put_info "constraint set prefer-oldest"
+run_cmd $CABAL v2-build $ARG_COMPILER --disable-tests --disable-benchmarks --dependencies-only -j all
+run_cmd $CABAL v2-build $ARG_COMPILER --disable-tests --disable-benchmarks all
 
 
 # Done
diff --git a/src/HaskellCI/Config/ConstraintSet.hs b/src/HaskellCI/Config/ConstraintSet.hs
index c5ab7d76..c5b931bf 100644
--- a/src/HaskellCI/Config/ConstraintSet.hs
+++ b/src/HaskellCI/Config/ConstraintSet.hs
@@ -11,15 +11,16 @@ import HaskellCI.Newtypes
 import HaskellCI.OptionsGrammar
 
 data ConstraintSet = ConstraintSet
-    { csName        :: String
-    , csGhcVersions :: VersionRange
-    , csGhcjs       :: Bool
-    , csConstraints :: [String] -- we parse these simply as strings
-    , csTests       :: Bool
-    , csRunTests    :: Bool
-    , csDocspec     :: Bool
-    , csBenchmarks  :: Bool
-    , csHaddock     :: Bool
+    { csName         :: String
+    , csGhcVersions  :: VersionRange
+    , csGhcjs        :: Bool
+    , csConstraints  :: [String] -- we parse these simply as strings
+    , csTests        :: Bool
+    , csRunTests     :: Bool
+    , csDocspec      :: Bool
+    , csBenchmarks   :: Bool
+    , csHaddock      :: Bool
+    , csPreferOldest :: Bool
     }
   deriving (Show, Generic)
 
@@ -40,3 +41,4 @@ constraintSetGrammar name = ConstraintSet name
     <*> C.booleanFieldDef  "docspec"                                       (field @"csDocspec") False
     <*> C.booleanFieldDef  "benchmarks"                                    (field @"csBenchmarks") False
     <*> C.booleanFieldDef  "haddock"                                       (field @"csHaddock") False
+    <*> C.booleanFieldDef  "prefer-oldest"                                 (field @"csPreferOldest") False
diff --git a/src/HaskellCI/GitHub.hs b/src/HaskellCI/GitHub.hs
index d34ad8f1..221f6f11 100644
--- a/src/HaskellCI/GitHub.hs
+++ b/src/HaskellCI/GitHub.hs
@@ -497,7 +497,8 @@ makeGitHub _argv config@Config {..} gitconfig prj jobs@JobVersions {..} = do
             let testFlag        = if csTests cs then "--enable-tests" else "--disable-tests"
             let benchFlag       = if csBenchmarks cs then "--enable-benchmarks" else "--disable-benchmarks"
             let constraintFlags = map (\x ->  "--constraint='" ++ x ++ "'") (csConstraints cs)
-            let allFlags        = unwords (testFlag : benchFlag : constraintFlags)
+            let preferFlags     = if csPreferOldest cs then ["--prefer-oldest"] else []
+            let allFlags        = unwords (testFlag : benchFlag : constraintFlags ++ preferFlags)
 
             sh_cs $ "$CABAL v2-build $ARG_COMPILER " ++ allFlags ++ " all --dry-run"
             sh_cs $ "cabal-plan topo | sort"