diff --git a/tests/utils/utils_test.ok b/tests/utils/utils_test.ok
index 3f453e9..6f5d46b 100644
--- a/tests/utils/utils_test.ok
+++ b/tests/utils/utils_test.ok
@@ -470,6 +470,60 @@
 more: 0001011100101010000 (need=19)
 10: 000101110 (need=9)
 
+strbuf_test_tail_for_buflen(64)
+1: "banananana\n" sb.chars_needed=11 sb.pos=&sb.buf[11]
+2: "bananana" sb.chars_needed=8 sb.pos=&sb.buf[8]
+3: "bananana\n" sb.chars_needed=9 sb.pos=&sb.buf[9]
+4: "banana" sb.chars_needed=6 sb.pos=&sb.buf[6]
+5: "banana\n" sb.chars_needed=7 sb.pos=&sb.buf[7]
+6: "banana" sb.chars_needed=6 sb.pos=&sb.buf[6]
+7: "bananabread\n" sb.chars_needed=12 sb.pos=&sb.buf[12]
+
+strbuf_test_tail_for_buflen(32)
+1: "banananana\n" sb.chars_needed=11 sb.pos=&sb.buf[11]
+2: "bananana" sb.chars_needed=8 sb.pos=&sb.buf[8]
+3: "bananana\n" sb.chars_needed=9 sb.pos=&sb.buf[9]
+4: "banana" sb.chars_needed=6 sb.pos=&sb.buf[6]
+5: "banana\n" sb.chars_needed=7 sb.pos=&sb.buf[7]
+6: "banana" sb.chars_needed=6 sb.pos=&sb.buf[6]
+7: "bananabread\n" sb.chars_needed=12 sb.pos=&sb.buf[12]
+
+strbuf_test_tail_for_buflen(16)
+1: "banananana\n" sb.chars_needed=11 sb.pos=&sb.buf[11]
+2: "bananana" sb.chars_needed=8 sb.pos=&sb.buf[8]
+3: "bananana\n" sb.chars_needed=9 sb.pos=&sb.buf[9]
+4: "banana" sb.chars_needed=6 sb.pos=&sb.buf[6]
+5: "banana\n" sb.chars_needed=7 sb.pos=&sb.buf[7]
+6: "banana" sb.chars_needed=6 sb.pos=&sb.buf[6]
+7: "bananabread\n" sb.chars_needed=12 sb.pos=&sb.buf[12]
+
+strbuf_test_tail_for_buflen(8)
+1: "bananan" sb.chars_needed=11 sb.pos=&sb.buf[8]
+2: "bananan" sb.chars_needed=8 sb.pos=&sb.buf[8]
+3: "bananan" sb.chars_needed=9 sb.pos=&sb.buf[8]
+4: "banana" sb.chars_needed=6 sb.pos=&sb.buf[6]
+5: "banana\n" sb.chars_needed=7 sb.pos=&sb.buf[7]
+6: "banana" sb.chars_needed=6 sb.pos=&sb.buf[6]
+7: "bananab" sb.chars_needed=12 sb.pos=&sb.buf[7]
+
+strbuf_test_tail_for_buflen(4)
+1: "ban" sb.chars_needed=11 sb.pos=&sb.buf[4]
+2: "ban" sb.chars_needed=8 sb.pos=&sb.buf[4]
+3: "ban" sb.chars_needed=9 sb.pos=&sb.buf[4]
+4: "ban" sb.chars_needed=6 sb.pos=&sb.buf[4]
+5: "ban" sb.chars_needed=7 sb.pos=&sb.buf[4]
+6: "ban" sb.chars_needed=6 sb.pos=&sb.buf[4]
+7: "ban" sb.chars_needed=12 sb.pos=&sb.buf[4]
+
+strbuf_test_tail_for_buflen(1)
+1: "" sb.chars_needed=11 sb.pos=&sb.buf[1]
+2: "" sb.chars_needed=8 sb.pos=&sb.buf[1]
+3: "" sb.chars_needed=9 sb.pos=&sb.buf[1]
+4: "" sb.chars_needed=6 sb.pos=&sb.buf[1]
+5: "" sb.chars_needed=7 sb.pos=&sb.buf[1]
+6: "" sb.chars_needed=6 sb.pos=&sb.buf[1]
+7: "" sb.chars_needed=12 sb.pos=&sb.buf[1]
+
 startswith_test()
 osmo_str_startswith(NULL, NULL) == true
 osmo_str_startswith("", NULL) == true