diff --git a/openbsc/src/libbsc/bts_nokia_site.c b/openbsc/src/libbsc/bts_nokia_site.c
index 4b5c50f..c43eb5f 100644
--- a/openbsc/src/libbsc/bts_nokia_site.c
+++ b/openbsc/src/libbsc/bts_nokia_site.c
@@ -84,7 +84,7 @@
   Attention: this has to be adapted for mISDN
 */
 
-void start_sabm_in_line(struct e1inp_line *line, int start, int sapi)
+static void start_sabm_in_line(struct e1inp_line *line, int start, int sapi)
 {
 	struct e1inp_sign_link *link;
 	int i;