diff --git a/Cargo.toml b/Cargo.toml
index c463ead..141734d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,7 +25,7 @@ doctest = false
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "2.0", features = ["full"] }
+syn = { version = "3.0", features = ["full"] }
 
 [dev-dependencies]
 serde = { version = "1.0", features = ["derive"] }
diff --git a/src/utils.rs b/src/utils.rs
index e6e93ef..11c2090 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -26,7 +26,7 @@ pub(crate) fn type_lifetimes_to_static(ty: &mut Type) {
                     }
                     PathArguments::Parenthesized(parenthesized) => {
                         for input in &mut parenthesized.inputs {
-                            type_lifetimes_to_static(input)
+                            type_lifetimes_to_static(&mut input.ty)
                         }
                     }
                 }