diff --git a/impl/Cargo.toml b/impl/Cargo.toml
index a52ab74f..16fdb9a8 100644
--- a/impl/Cargo.toml
+++ b/impl/Cargo.toml
@@ -25,7 +25,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = "2.0"
+syn = "2.0.45"
 convert_case = { version = "0.6", optional = true }
 unicode-xid = { version = "0.2.2", optional = true }
 
diff --git a/tests/debug.rs b/tests/debug.rs
index d2ca8776..9b1e45a8 100644
--- a/tests/debug.rs
+++ b/tests/debug.rs
@@ -1914,3 +1914,21 @@ mod generic {
         }
     }
 }
+
+// See: https://github.com/JelteF/derive_more/issues/301
+mod complex_enum_syntax {
+    #[cfg(not(feature = "std"))]
+    use alloc::{boxed::Box, format};
+
+    use derive_more::Debug;
+
+    #[derive(Debug)]
+    enum Enum {
+        A = if cfg!(unix) { 2 } else { 3 },
+    }
+
+    #[test]
+    fn assert() {
+        assert_eq!(format!("{:?}", Enum::A), "A");
+    }
+}