diff --git a/src/kirin/dialects/scf/stmts.py b/src/kirin/dialects/scf/stmts.py
index 3c4ea008f..6348b8b5d 100644
--- a/src/kirin/dialects/scf/stmts.py
+++ b/src/kirin/dialects/scf/stmts.py
@@ -41,7 +41,7 @@ def __init__(
                 then_body_block = None
         else:  # then_body.IS_BLOCK:
             then_body_block = cast(Block, then_body)
-            then_body_region = cast(Region, then_body)
+            then_body_region = Region(then_body_block)
 
         if else_body is None:
             else_body_region = ir.Region()
diff --git a/test/dialects/scf/test_ifelse.py b/test/dialects/scf/test_ifelse.py
index c5cdcf906..86f35dbda 100644
--- a/test/dialects/scf/test_ifelse.py
+++ b/test/dialects/scf/test_ifelse.py
@@ -3,7 +3,7 @@
 from kirin import ir
 from kirin.passes import Fold
 from kirin.prelude import python_basic
-from kirin.dialects import scf, func, lowering
+from kirin.dialects import py, scf, func, lowering
 
 # TODO:
 # test_cons
@@ -150,3 +150,19 @@ def main(n: int):
     assert main(2) == 1.0
     assert main(1) == 1.0
     assert main(0) == 0.0
+
+
+def test_manual_construct_ifelse_from_blocks():
+    scf.IfElse(
+        cond=ir.TestValue(),
+        then_body=ir.Block(
+            stmts=[
+                py.Constant(5),
+            ],
+        ),
+        else_body=ir.Block(
+            stmts=[
+                py.Constant(11),
+            ],
+        ),
+    )