diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index 133049e95a..e8dcfea538 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -544,6 +544,9 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 	// TODO generics
 	args, _, is_variadic := p.fn_args()
 	for arg in args {
+		if arg.name.len == 0 {
+			p.error_with_pos('use `_` to name an unused parameter', arg.pos)
+		}
 		p.scope.register(ast.Var{
 			name: arg.name
 			typ: arg.typ
diff --git a/vlib/v/parser/tests/anon_unused_param.out b/vlib/v/parser/tests/anon_unused_param.out
new file mode 100644
index 0000000000..a12769b300
--- /dev/null
+++ b/vlib/v/parser/tests/anon_unused_param.out
@@ -0,0 +1,4 @@
+vlib/v/parser/tests/anon_unused_param.vv:1:9: error: use `_` to name an unused parameter
+    1 | _ = fn (int){}
+      |         ~~~
+    2 |
diff --git a/vlib/v/parser/tests/anon_unused_param.vv b/vlib/v/parser/tests/anon_unused_param.vv
new file mode 100644
index 0000000000..c285cea3c9
--- /dev/null
+++ b/vlib/v/parser/tests/anon_unused_param.vv
@@ -0,0 +1,2 @@
+_ = fn (int){}
+