diff --git a/tests/unittests/tests-chunked_ringbuffer/tests-chunked_ringbuffer.c b/tests/unittests/tests-chunked_ringbuffer/tests-chunked_ringbuffer.c
index d2020ebf322a..5d69ea98a2fb 100644
--- a/tests/unittests/tests-chunked_ringbuffer/tests-chunked_ringbuffer.c
+++ b/tests/unittests/tests-chunked_ringbuffer/tests-chunked_ringbuffer.c
@@ -25,6 +25,12 @@ static void test_crb_add_and_consume(void)
 
     crb_init(&cb, buffer, sizeof(buffer));
 
+    /* add a chunk but don't finish it */
+    crb_start_chunk(&cb);
+    crb_add_byte(&cb, 1);
+    crb_add_byte(&cb, 2);
+    crb_add_byte(&cb, 3);
+
     TEST_ASSERT(crb_add_chunk(&cb, "one", 4));
     TEST_ASSERT(crb_add_chunk(&cb, "two", 4));
     TEST_ASSERT(crb_add_chunk(&cb, "three", 6));