diff --git a/src/ops/mul_add.rs b/src/ops/mul_add.rs
index 284ee9f..cf7bd2c 100644
--- a/src/ops/mul_add.rs
+++ b/src/ops/mul_add.rs
@@ -67,6 +67,8 @@ macro_rules! mul_add_impl {
 }
 
 mul_add_impl!(MulAdd for isize usize i8 u8 i16 u16 i32 u32 i64 u64);
+#[cfg(feature = "i128")]
+mul_add_impl!(MulAdd for i128 u128);
 
 #[cfg(feature = "std")]
 impl MulAddAssign<f32, f32> for f32 {
@@ -96,6 +98,8 @@ macro_rules! mul_add_assign_impl {
 }
 
 mul_add_assign_impl!(MulAddAssign for isize usize i8 u8 i16 u16 i32 u32 i64 u64);
+#[cfg(feature = "i128")]
+mul_add_assign_impl!(MulAddAssign for i128 u128);
 
 #[cfg(test)]
 mod tests {