diff --git a/tests/peg-parser/test-gbnf-generation.cpp b/tests/peg-parser/test-gbnf-generation.cpp
index fe4bbbdd16..00111e6a19 100644
--- a/tests/peg-parser/test-gbnf-generation.cpp
+++ b/tests/peg-parser/test-gbnf-generation.cpp
@@ -129,7 +129,7 @@ void test_gbnf_generation(testing &t) {
         });
 
         assert_gbnf_equal(t, R"""(
-            root ::= ([^<] | "<" [^/] | "</" [^t] | "</t" [^a] | "</ta" [^g] | "</tag" [^>])*
+            root ::= ([^<] | "<" [^/] | "</" [^t] | "</t" [^a] | "</ta" [^g] | "</tag" [^>])* ("<" | "</" | "</t" | "</ta" | "</tag")?
             space ::= | " " | "\n"{1,2} [ \t]{0,20}
         )""", gbnf);
     });