diff --git a/testsuite/sexp-format-test.c b/testsuite/sexp-format-test.c
index b87c25380ee26ccf9d51e0e78ac27892d809e48d..2d8457b1a8a5fdd1d0093b4b951fbf3ffcccd6cc 100644
--- a/testsuite/sexp-format-test.c
+++ b/testsuite/sexp-format-test.c
@@ -106,6 +106,21 @@ test_main(void)
     ASSERT(MEMEQ(buffer.size, buffer.contents, e));
   }
 
+  /* Literal parenthesis */
+  {
+    const uint8_t e[] = ")3:foo(3:bar";
+
+    nettle_buffer_init(&buffer);
+    ASSERT(sexp_format(&buffer, "%)foo%(%s", 3, "bar")
+	   == strlen(e));
+    
+    ASSERT(sexp_format(NULL, "%)foo%(%s", 3, "bar")
+	   == strlen(e));
+    
+    ASSERT(buffer.size == strlen(e));
+    ASSERT(MEMEQ(buffer.size, buffer.contents, e));
+  }
+  
 #if HAVE_LIBGMP
   {
     mpz_t x;