diff --git a/compiler/rustc_attr_parsing/src/attributes/diagnostic/on_unmatched_args.rs b/compiler/rustc_attr_parsing/src/attributes/diagnostic/on_unmatched_args.rs
index 18f980bfebbe8..df8cee63506cc 100644
--- a/compiler/rustc_attr_parsing/src/attributes/diagnostic/on_unmatched_args.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/diagnostic/on_unmatched_args.rs
@@ -17,6 +17,8 @@ impl AttributeParser for OnUnmatchedArgsParser {
         AttributeStability::Stable, // Unstable, stability checked manually in the parser
         |this, cx, args| {
             if !cx.features().diagnostic_on_unmatched_args() {
+                // `UnknownDiagnosticAttribute` is emitted in rustc_resolve/macros.rs
+                args.ignore_args();
                 return;
             }
 
diff --git a/tests/ui/diagnostic_namespace/on_unmatched_args/disabled-feature-issue-159886.rs b/tests/ui/diagnostic_namespace/on_unmatched_args/disabled-feature-issue-159886.rs
new file mode 100644
index 0000000000000..0892844f51372
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/on_unmatched_args/disabled-feature-issue-159886.rs
@@ -0,0 +1,12 @@
+//@ check-pass
+//@ needs-rustc-debug-assertions
+
+#![allow(unknown_or_malformed_diagnostic_attributes)]
+#![allow(unused_macros)]
+
+#[diagnostic::on_unmatched_args(message)]
+macro_rules! pair {
+    () => {};
+}
+
+fn main() {}