diff --git a/babeld/util.c b/babeld/util.c
index f1ac0f1..514e0ff 100644
--- a/babeld/util.c
+++ b/babeld/util.c
@@ -298,6 +298,10 @@
     return buf[i];
 }
 
+const char *format_bool(const int b) {
+    return b ? "true" : "false";
+}
+
 int
 parse_address(const char *address, unsigned char *addr_r, int *af_r)
 {