diff --git a/lib/haskell/conformance.sh b/lib/haskell/conformance.sh
index 0c34a35c..4c64ea32 100755
--- a/lib/haskell/conformance.sh
+++ b/lib/haskell/conformance.sh
@@ -39,6 +39,7 @@ run_suite() {
 (load "lib/haskell/match.sx")
 (load "lib/haskell/eval.sx")
 (load "lib/haskell/map.sx")
+(load "lib/haskell/set.sx")
 (load "lib/haskell/testlib.sx")
 (epoch 2)
 (load "$FILE")
diff --git a/lib/haskell/eval.sx b/lib/haskell/eval.sx
index bcf9087f..1692cc20 100644
--- a/lib/haskell/eval.sx
+++ b/lib/haskell/eval.sx
@@ -1123,6 +1123,89 @@
                   (:else (hk-force d)))))
             3))))))
 
+(define
+  hk-bind-data-set!
+  (fn
+    (env alias)
+    (let
+      ((p (str alias ".")))
+      (begin
+        (dict-set! env (str p "empty") hk-set-empty)
+        (dict-set!
+          env
+          (str p "singleton")
+          (hk-mk-lazy-builtin
+            "Set.singleton"
+            (fn (k) (hk-set-singleton (hk-force k)))
+            1))
+        (dict-set!
+          env
+          (str p "insert")
+          (hk-mk-lazy-builtin
+            "Set.insert"
+            (fn (k s) (hk-set-insert (hk-force k) (hk-force s)))
+            2))
+        (dict-set!
+          env
+          (str p "delete")
+          (hk-mk-lazy-builtin
+            "Set.delete"
+            (fn (k s) (hk-set-delete (hk-force k) (hk-force s)))
+            2))
+        (dict-set!
+          env
+          (str p "member")
+          (hk-mk-lazy-builtin
+            "Set.member"
+            (fn
+              (k s)
+              (hk-of-bool (hk-set-member (hk-force k) (hk-force s))))
+            2))
+        (dict-set!
+          env
+          (str p "size")
+          (hk-mk-lazy-builtin
+            "Set.size"
+            (fn (s) (hk-set-size (hk-force s)))
+            1))
+        (dict-set!
+          env
+          (str p "null")
+          (hk-mk-lazy-builtin
+            "Set.null"
+            (fn (s) (hk-of-bool (hk-set-null (hk-force s))))
+            1))
+        (dict-set!
+          env
+          (str p "union")
+          (hk-mk-lazy-builtin
+            "Set.union"
+            (fn (a b) (hk-set-union (hk-force a) (hk-force b)))
+            2))
+        (dict-set!
+          env
+          (str p "intersection")
+          (hk-mk-lazy-builtin
+            "Set.intersection"
+            (fn (a b) (hk-set-intersection (hk-force a) (hk-force b)))
+            2))
+        (dict-set!
+          env
+          (str p "difference")
+          (hk-mk-lazy-builtin
+            "Set.difference"
+            (fn (a b) (hk-set-difference (hk-force a) (hk-force b)))
+            2))
+        (dict-set!
+          env
+          (str p "isSubsetOf")
+          (hk-mk-lazy-builtin
+            "Set.isSubsetOf"
+            (fn
+              (a b)
+              (hk-of-bool (hk-set-is-subset-of (hk-force a) (hk-force b))))
+            2))))))
+
 (define
   hk-bind-decls!
   (fn
@@ -1280,9 +1363,15 @@
               (let
                 ((modname (nth d 2)) (as-name (nth d 3)))
                 (let
-                  ((alias (cond ((nil? as-name) "Map") (:else as-name))))
+                  ((alias
+                      (cond
+                        ((not (nil? as-name)) as-name)
+                        ((= modname "Data.Map") "Map")
+                        ((= modname "Data.Set") "Set")
+                        (:else modname))))
                   (cond
                     ((= modname "Data.Map") (hk-bind-data-map! env alias))
+                    ((= modname "Data.Set") (hk-bind-data-set! env alias))
                     (:else nil)))))
             (:else nil)))
         decls)
diff --git a/lib/haskell/test.sh b/lib/haskell/test.sh
index 59aa8b2f..d0af750a 100755
--- a/lib/haskell/test.sh
+++ b/lib/haskell/test.sh
@@ -56,6 +56,7 @@ for FILE in "${FILES[@]}"; do
 (load "lib/haskell/match.sx")
 (load "lib/haskell/eval.sx")
 (load "lib/haskell/map.sx")
+(load "lib/haskell/set.sx")
 $INFER_LOAD
 (load "lib/haskell/testlib.sx")
 (epoch 2)
@@ -100,6 +101,7 @@ EPOCHS
 (load "lib/haskell/match.sx")
 (load "lib/haskell/eval.sx")
 (load "lib/haskell/map.sx")
+(load "lib/haskell/set.sx")
 $INFER_LOAD
 (load "lib/haskell/testlib.sx")
 (epoch 2)
diff --git a/plans/haskell-completeness.md b/plans/haskell-completeness.md
index 8f16f145..7ef38acb 100644
--- a/plans/haskell-completeness.md
+++ b/plans/haskell-completeness.md
@@ -209,7 +209,7 @@ No OCaml changes are needed. The view type is fully representable as an SX dict.
 - [x] API: `empty`, `singleton`, `insert`, `delete`, `member`, `fromList`,
   `toList`, `toAscList`, `size`, `null`, `union`, `intersection`, `difference`,
   `isSubsetOf`, `filter`, `map`, `foldr`, `foldl'`.
-- [ ] Module wiring: `import Data.Set` / `import qualified Data.Set as Set`.
+- [x] Module wiring: `import Data.Set` / `import qualified Data.Set as Set`.
 - [ ] Unit tests in `lib/haskell/tests/set.sx` (≥ 15 tests: empty, insert,
   member hit/miss, delete, fromList deduplication, union, intersection,
   difference, isSubsetOf).
@@ -307,6 +307,16 @@ No OCaml changes are needed. The view type is fully representable as an SX dict.
 
 _Newest first._
 
+**2026-05-07** — Phase 12 module wiring: `import Data.Set`:
+- New `hk-bind-data-set!` registers `Set.empty/singleton/insert/delete/
+  member/size/null/union/intersection/difference/isSubsetOf` as Haskell
+  builtins.
+- Import handler now dispatches on modname: `Data.Map` → `hk-bind-data-map!`,
+  `Data.Set` → `hk-bind-data-set!`. Default alias is now derived from the
+  modname suffix instead of being hardcoded `Map` (was a bug for `Data.Set`).
+- `test.sh` and `conformance.sh` load `set.sx` after `map.sx`.
+- Verified `Set.size`, `Set.member`, `Set.union`, `Set.insert` from Haskell.
+
 **2026-05-07** — Phase 12 Data.Set full API:
 - Added `from-list`/`union`/`intersection`/`difference`/`is-subset-of`/
   `filter`/`map`/`foldr`/`foldl` — all delegate to the corresponding