diff --git a/src/parse.rs b/src/parse.rs
index 020fffe..bbae32b 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -60,7 +60,14 @@ use std::iter::Peekable;
 
 pub fn parse_declaration(tokens: TokenStream) -> Result<Declaration, Error> {
     let mut tokens = tokens.into_iter().peekable();
-    parse_declaration_tokens(&mut tokens)
+    let declaration = parse_declaration_tokens(&mut tokens);
+    if tokens.peek().is_some() {
+        panic!(
+            "cannot parse declaration, unexpected trailing tokens: {}",
+            tokens.collect::<TokenStream>()
+        );
+    }
+    declaration
 }
 
 pub(crate) fn parse_declaration_tokens(
diff --git a/src/tests.rs b/src/tests.rs
index 4a0f738..a244f2a 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -122,6 +122,12 @@ fn parse_empty_enum() {
     assert_debug_snapshot!(enum_type);
 }
 
+#[test]
+#[should_panic]
+fn reject_trailing_junk() {
+    dbg!(parse_declaration(quote::quote! {struct Good {} bad})).unwrap();
+}
+
 // ==========
 // VISIBILITY
 // ==========