diff --git a/serde/src/integer128.rs b/serde/src/integer128.rs
new file mode 100644
index 00000000..169c7128
--- /dev/null
+++ b/serde/src/integer128.rs
@@ -0,0 +1,15 @@
+/// TODO: rustdoc
+#[cfg(integer128)]
+#[macro_export]
+macro_rules! serde_if_integer128 {
+    ($($tt:tt)*) => {
+        $($tt)*
+    };
+}
+
+#[cfg(not(integer128))]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! serde_if_integer128 {
+    ($($tt:tt)*) => {};
+}
diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index a304fd74..ccd70929 100644
--- a/serde/src/lib.rs
+++ b/serde/src/lib.rs
@@ -222,6 +222,9 @@ mod lib {
 #[macro_use]
 mod macros;
 
+#[macro_use]
+mod integer128;
+
 pub mod de;
 pub mod ser;