diff --git a/glean/test/lib/TestData.hs b/glean/test/lib/TestData.hs
index 1b1e9c17e..e71d75a81 100644
--- a/glean/test/lib/TestData.hs
+++ b/glean/test/lib/TestData.hs
@@ -15,6 +15,7 @@ module TestData
   ) where
 
 import Data.Default
+import qualified Data.Set as Set
 
 import Glean.Typed
 import Glean.Types
@@ -42,8 +43,9 @@ kitchenSink1 = def
   , Glean.Test.kitchenSink_maybe_ = Just def
   , Glean.Test.kitchenSink_bool_ = True
   , Glean.Test.kitchenSink_string_ = "Hello\0world!\0"
-  , Glean.Test.kitchenSink_set_of_nat = [toNat 65535, toNat 1, toNat 2 ]
-  , Glean.Test.kitchenSink_set_of_string = ["apa", "bepa"]
+  , Glean.Test.kitchenSink_set_of_nat =
+      Set.fromList [toNat 65535, toNat 1, toNat 2 ]
+  , Glean.Test.kitchenSink_set_of_string = Set.fromList ["apa", "bepa"]
   }
 
 mkTestFacts :: NewFact m => (m () -> m ()) -> (m () -> m ()) -> m ()
@@ -106,7 +108,7 @@ mkTestFacts first second = do
       , Glean.Test.kitchenSink_named_sum_ = Glean.Test.Sum_wed True
       , Glean.Test.kitchenSink_named_record_ = rec
       , Glean.Test.kitchenSink_maybe_ = Nothing
-      , Glean.Test.kitchenSink_set_of_pred = [kitchenSink2Fact0]
+      , Glean.Test.kitchenSink_set_of_pred = Set.fromList [kitchenSink2Fact0]
       }
 
     kitchenSink2Term1b = kitchenSink2Term1