diff --git a/src/de.rs b/src/de.rs
index d2c7a32b..e5f21b06 100644
--- a/src/de.rs
+++ b/src/de.rs
@@ -4,7 +4,6 @@ use serde::de::{
     self, Deserialize, DeserializeOwned, DeserializeSeed, Expected, IgnoredAny as Ignore,
     IntoDeserializer, Unexpected, Visitor,
 };
-use serde::serde_if_integer128;
 use std::collections::BTreeMap;
 use std::f64;
 use std::fmt;
@@ -261,13 +260,11 @@ impl<'de> de::Deserializer<'de> for Deserializer<'de> {
         self.de(|state| state.deserialize_i64(visitor))
     }
 
-    serde_if_integer128! {
-        fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value>
-        where
-            V: Visitor<'de>,
-        {
-            self.de(|state| state.deserialize_i128(visitor))
-        }
+    fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value>
+    where
+        V: Visitor<'de>,
+    {
+        self.de(|state| state.deserialize_i128(visitor))
     }
 
     fn deserialize_u8<V>(self, visitor: V) -> Result<V::Value>
@@ -298,13 +295,11 @@ impl<'de> de::Deserializer<'de> for Deserializer<'de> {
         self.de(|state| state.deserialize_u64(visitor))
     }
 
-    serde_if_integer128! {
-        fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value>
-        where
-            V: Visitor<'de>,
-        {
-            self.de(|state| state.deserialize_u128(visitor))
-        }
+    fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value>
+    where
+        V: Visitor<'de>,
+    {
+        self.de(|state| state.deserialize_u128(visitor))
     }
 
     fn deserialize_f32<V>(self, visitor: V) -> Result<V::Value>
@@ -1002,18 +997,14 @@ where
     if let Ok(n) = v.parse() {
         return visitor.visit_u64(n);
     }
-    serde_if_integer128! {
-        if let Ok(n) = v.parse() {
-            return visitor.visit_u128(n);
-        }
+    if let Ok(n) = v.parse() {
+        return visitor.visit_u128(n);
     }
     if let Ok(n) = v.parse() {
         return visitor.visit_i64(n);
     }
-    serde_if_integer128! {
-        if let Ok(n) = v.parse() {
-            return visitor.visit_i128(n);
-        }
+    if let Ok(n) = v.parse() {
+        return visitor.visit_i128(n);
     }
     match trim_start_matches(v, '+') {
         ".inf" | ".Inf" | ".INF" => return visitor.visit_f64(f64::INFINITY),
@@ -1143,13 +1134,11 @@ impl<'de, 'a, 'r> de::Deserializer<'de> for &'r mut DeserializerFromEvents<'a> {
         self.deserialize_scalar(visitor)
     }
 
-    serde_if_integer128! {
-        fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value>
-        where
-            V: Visitor<'de>,
-        {
-            self.deserialize_scalar(visitor)
-        }
+    fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value>
+    where
+        V: Visitor<'de>,
+    {
+        self.deserialize_scalar(visitor)
     }
 
     fn deserialize_u8<V>(self, visitor: V) -> Result<V::Value>
@@ -1180,13 +1169,11 @@ impl<'de, 'a, 'r> de::Deserializer<'de> for &'r mut DeserializerFromEvents<'a> {
         self.deserialize_scalar(visitor)
     }
 
-    serde_if_integer128! {
-        fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value>
-        where
-            V: Visitor<'de>,
-        {
-            self.deserialize_scalar(visitor)
-        }
+    fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value>
+    where
+        V: Visitor<'de>,
+    {
+        self.deserialize_scalar(visitor)
     }
 
     fn deserialize_f32<V>(self, visitor: V) -> Result<V::Value>
diff --git a/src/ser.rs b/src/ser.rs
index f97efa50..6b7ceb7a 100644
--- a/src/ser.rs
+++ b/src/ser.rs
@@ -3,7 +3,7 @@
 //! This module provides YAML serialization with the type `Serializer`.
 
 use crate::{error, Error, Result};
-use serde::{ser, serde_if_integer128};
+use serde::ser;
 use std::{fmt, io, num, str};
 use yaml_rust::{yaml, Yaml, YamlEmitter};
 
@@ -109,11 +109,9 @@ where
         self.write(doc)
     }
 
-    serde_if_integer128! {
-        fn serialize_i128(self, v: i128) -> Result<()> {
-            let doc = SerializerToYaml.serialize_i128(v)?;
-            self.write(doc)
-        }
+    fn serialize_i128(self, v: i128) -> Result<()> {
+        let doc = SerializerToYaml.serialize_i128(v)?;
+        self.write(doc)
     }
 
     fn serialize_u8(self, v: u8) -> Result<()> {
@@ -136,11 +134,9 @@ where
         self.write(doc)
     }
 
-    serde_if_integer128! {
-        fn serialize_u128(self, v: u128) -> Result<()> {
-            let doc = SerializerToYaml.serialize_u128(v)?;
-            self.write(doc)
-        }
+    fn serialize_u128(self, v: u128) -> Result<()> {
+        let doc = SerializerToYaml.serialize_u128(v)?;
+        self.write(doc)
     }
 
     fn serialize_f32(self, v: f32) -> Result<()> {
@@ -479,14 +475,12 @@ impl ser::Serializer for SerializerToYaml {
         Ok(Yaml::Integer(v))
     }
 
-    serde_if_integer128! {
-        #[allow(clippy::cast_possible_truncation)]
-        fn serialize_i128(self, v: i128) -> Result<Yaml> {
-            if v <= i64::max_value() as i128 && v >= i64::min_value() as i128 {
-                self.serialize_i64(v as i64)
-            } else {
-                Ok(Yaml::Real(v.to_string()))
-            }
+    #[allow(clippy::cast_possible_truncation)]
+    fn serialize_i128(self, v: i128) -> Result<Yaml> {
+        if v <= i64::max_value() as i128 && v >= i64::min_value() as i128 {
+            self.serialize_i64(v as i64)
+        } else {
+            Ok(Yaml::Real(v.to_string()))
         }
     }
 
@@ -510,14 +504,12 @@ impl ser::Serializer for SerializerToYaml {
         }
     }
 
-    serde_if_integer128! {
-        #[allow(clippy::cast_possible_truncation)]
-        fn serialize_u128(self, v: u128) -> Result<Yaml> {
-            if v <= i64::max_value() as u128 {
-                self.serialize_i64(v as i64)
-            } else {
-                Ok(Yaml::Real(v.to_string()))
-            }
+    #[allow(clippy::cast_possible_truncation)]
+    fn serialize_u128(self, v: u128) -> Result<Yaml> {
+        if v <= i64::max_value() as u128 {
+            self.serialize_i64(v as i64)
+        } else {
+            Ok(Yaml::Real(v.to_string()))
         }
     }
 
diff --git a/src/value/de.rs b/src/value/de.rs
index 6d4f8c0b..61e04696 100644
--- a/src/value/de.rs
+++ b/src/value/de.rs
@@ -3,7 +3,7 @@ use serde::de::{
     self, Deserialize, DeserializeSeed, Deserializer, EnumAccess, Error as SError, Expected,
     MapAccess, SeqAccess, Unexpected, VariantAccess, Visitor,
 };
-use serde::{forward_to_deserialize_any, serde_if_integer128};
+use serde::forward_to_deserialize_any;
 use std::fmt;
 use std::vec;
 
@@ -212,13 +212,11 @@ impl<'de> Deserializer<'de> for Value {
         self.deserialize_number(visitor)
     }
 
-    serde_if_integer128! {
-        fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value, Error>
-        where
-            V: Visitor<'de>,
-        {
-            self.deserialize_number(visitor)
-        }
+    fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value, Error>
+    where
+        V: Visitor<'de>,
+    {
+        self.deserialize_number(visitor)
     }
 
     fn deserialize_u8<V>(self, visitor: V) -> Result<V::Value, Error>
@@ -249,13 +247,11 @@ impl<'de> Deserializer<'de> for Value {
         self.deserialize_number(visitor)
     }
 
-    serde_if_integer128! {
-        fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value, Error>
-        where
-            V: Visitor<'de>,
-        {
-            self.deserialize_number(visitor)
-        }
+    fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value, Error>
+    where
+        V: Visitor<'de>,
+    {
+        self.deserialize_number(visitor)
     }
 
     fn deserialize_f32<V>(self, visitor: V) -> Result<V::Value, Error>
diff --git a/tests/test_de.rs b/tests/test_de.rs
index 3e2c8fa5..9d7b5bc6 100644
--- a/tests/test_de.rs
+++ b/tests/test_de.rs
@@ -1,7 +1,6 @@
 #![allow(clippy::cast_lossless, clippy::cast_possible_wrap)]
 
 use indoc::indoc;
-use serde::serde_if_integer128;
 use serde_derive::Deserialize;
 use serde_yaml::Value;
 use std::collections::BTreeMap;
@@ -196,26 +195,24 @@ fn test_number_as_string() {
     test_de(yaml, &expected);
 }
 
-serde_if_integer128! {
-    #[test]
-    fn test_i128_big() {
-        let expected: i128 = ::std::i64::MIN as i128 - 1;
-        let yaml = indoc! {"
-            ---
-            -9223372036854775809
-        "};
-        assert_eq!(expected, serde_yaml::from_str::<i128>(yaml).unwrap());
-    }
+#[test]
+fn test_i128_big() {
+    let expected: i128 = ::std::i64::MIN as i128 - 1;
+    let yaml = indoc! {"
+        ---
+        -9223372036854775809
+    "};
+    assert_eq!(expected, serde_yaml::from_str::<i128>(yaml).unwrap());
+}
 
-    #[test]
-    fn test_u128_big() {
-        let expected: u128 = ::std::u64::MAX as u128 + 1;
-        let yaml = indoc! {"
-            ---
-            18446744073709551616
-        "};
-        assert_eq!(expected, serde_yaml::from_str::<u128>(yaml).unwrap());
-    }
+#[test]
+fn test_u128_big() {
+    let expected: u128 = ::std::u64::MAX as u128 + 1;
+    let yaml = indoc! {"
+        ---
+        18446744073709551616
+    "};
+    assert_eq!(expected, serde_yaml::from_str::<u128>(yaml).unwrap());
 }
 
 #[test]
diff --git a/tests/test_serde.rs b/tests/test_serde.rs
index 3576ae52..734998c2 100644
--- a/tests/test_serde.rs
+++ b/tests/test_serde.rs
@@ -5,7 +5,6 @@
 )]
 
 use indoc::indoc;
-use serde::serde_if_integer128;
 use serde_derive::{Deserialize, Serialize};
 use serde_yaml::Value;
 use std::collections::BTreeMap;
@@ -78,26 +77,24 @@ fn test_int_max_i64() {
     test_serde(&thing, yaml);
 }
 
-serde_if_integer128! {
-    #[test]
-    fn test_i128_small() {
-        let thing: i128 = -256;
-        let yaml = indoc! {"
-            ---
-            -256
-        "};
-        test_serde(&thing, yaml);
-    }
+#[test]
+fn test_i128_small() {
+    let thing: i128 = -256;
+    let yaml = indoc! {"
+        ---
+        -256
+    "};
+    test_serde(&thing, yaml);
+}
 
-    #[test]
-    fn test_u128_small() {
-        let thing: u128 = 256;
-        let yaml = indoc! {"
-            ---
-            256
-        "};
-        test_serde(&thing, yaml);
-    }
+#[test]
+fn test_u128_small() {
+    let thing: u128 = 256;
+    let yaml = indoc! {"
+        ---
+        256
+    "};
+    test_serde(&thing, yaml);
 }
 
 #[test]