diff --git a/src/Jikka/CPlusPlus/Language/Expr.hs b/src/Jikka/CPlusPlus/Language/Expr.hs
index fdeda591..e9f76132 100644
--- a/src/Jikka/CPlusPlus/Language/Expr.hs
+++ b/src/Jikka/CPlusPlus/Language/Expr.hs
@@ -57,8 +57,10 @@ data Monoid'
     MonoidIntMin
   | -- | \((\mathrm{int64\_t}, \max, \mathrm{INT64\_MIN})\)
     MonoidIntMax
-  | MonoidIntGcd
-  | MonoidIntLcm
+  | -- | \((\mathbb{Z}, \gcd, 0)\)
+    MonoidIntGcd
+  | -- | \((\mathbb{Z}, \mathrm{lcm}, 1)\)
+    MonoidIntLcm
   deriving (Eq, Ord, Show, Read)
 
 data Literal
diff --git a/src/Jikka/Core/Evaluate.hs b/src/Jikka/Core/Evaluate.hs
index 8037a18c..921f9763 100644
--- a/src/Jikka/Core/Evaluate.hs
+++ b/src/Jikka/Core/Evaluate.hs
@@ -114,6 +114,8 @@ segmentTreeGetRange semigrp segtree l r
           SemigroupIntPlus -> sum slice
           SemigroupIntMin -> minimum slice
           SemigroupIntMax -> maximum slice
+          SemigroupIntGcd -> foldl gcd 0 slice
+          SemigroupIntLcm -> foldl lcm 1 slice
 
 build :: MonadError Error m => (V.Vector Value -> m Value) -> V.Vector Value -> Integer -> m (V.Vector Value)
 build _ _ n | n < 0 = throwRuntimeError $ "negative length: " ++ show n
@@ -223,6 +225,8 @@ callBuiltin builtin ts args = wrapError' ("while calling builtin " ++ formatBuil
     Max1 -> go1 valueToList id (V.maximumBy compareValues')
     ArgMin -> go1 valueToList ValInt $ \xs -> snd (minimumBy (\(x, i) (y, j) -> compareValues' x y <> compare i j) (zip (V.toList xs) [0 ..]))
     ArgMax -> go1 valueToList ValInt $ \xs -> snd (maximumBy (\(x, i) (y, j) -> compareValues' x y <> compare i j) (zip (V.toList xs) [0 ..]))
+    Gcd1 -> go1 valueToIntList ValInt (foldl gcd 0)
+    Lcm1 -> go1 valueToIntList ValInt (foldl lcm 1)
     All -> go1 valueToBoolList ValBool and
     Any -> go1 valueToBoolList ValBool or
     Sorted -> go1 valueToList ValList sortVector
diff --git a/src/Jikka/Core/Language/Util.hs b/src/Jikka/Core/Language/Util.hs
index e2c7ee05..e80881b4 100644
--- a/src/Jikka/Core/Language/Util.hs
+++ b/src/Jikka/Core/Language/Util.hs
@@ -274,6 +274,8 @@ isConstantTimeBuiltin = \case
   Max1 -> False
   ArgMin -> False
   ArgMax -> False
+  Gcd1 -> False
+  Lcm1 -> False
   All -> False
   Any -> False
   Sorted -> False