diff --git a/openbsc/tests/bsc-nat/prefixes.csv b/openbsc/tests/bsc-nat/prefixes.csv
index 0b66ffe..0c7660f 100644
--- a/openbsc/tests/bsc-nat/prefixes.csv
+++ b/openbsc/tests/bsc-nat/prefixes.csv
@@ -1 +1,2 @@
 0172,0049
++49,0