diff --git a/test/parallel/test-debug-protocol-execute.js b/test/parallel/test-debug-protocol-execute.js
new file mode 100644
index 00000000000000..e87b25f5cb45da
--- /dev/null
+++ b/test/parallel/test-debug-protocol-execute.js
@@ -0,0 +1,20 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const debug = require('_debugger');
+
+const protocol = new debug.Protocol();
+
+assert.strictEqual(protocol.state, 'headers');
+
+protocol.execute('Content-Length: 10\r\n\r\nfhqwhgads');
+
+assert.strictEqual(protocol.state, 'body');
+assert.strictEqual(protocol.res.body, undefined);
+
+protocol.state = 'sterrance';
+assert.throws(
+	() => { protocol.execute('grumblecakes'); },
+	/^Error: Unknown state$/
+);