diff --git a/openbsc/include/openbsc/bsc_nat.h b/openbsc/include/openbsc/bsc_nat.h
index b3a12f5..ed1e5cd 100644
--- a/openbsc/include/openbsc/bsc_nat.h
+++ b/openbsc/include/openbsc/bsc_nat.h
@@ -292,4 +292,7 @@
 
 int bsc_write(struct bsc_connection *bsc, struct msgb *msg, int id);
 
+/* regexp handling */
+void bsc_parse_reg(void *ctx, regex_t *reg, char **imsi, int argc, const char **argv);
+
 #endif
diff --git a/openbsc/src/nat/bsc_nat_utils.c b/openbsc/src/nat/bsc_nat_utils.c
index 6baa952..275ecb4 100644
--- a/openbsc/src/nat/bsc_nat_utils.c
+++ b/openbsc/src/nat/bsc_nat_utils.c
@@ -272,3 +272,17 @@
 		return 0;
 	}
 }
+
+void bsc_parse_reg(void *ctx, regex_t *reg, char **imsi, int argc, const char **argv)
+{
+	if (*imsi) {
+		talloc_free(*imsi);
+		*imsi = NULL;
+	}
+	regfree(reg);
+
+	if (argc > 0) {
+		*imsi = talloc_strdup(ctx, argv[0]);
+		regcomp(reg, argv[0], 0);
+	}
+}
diff --git a/openbsc/src/nat/bsc_nat_vty.c b/openbsc/src/nat/bsc_nat_vty.c
index c24f7e5..9688de3 100644
--- a/openbsc/src/nat/bsc_nat_vty.c
+++ b/openbsc/src/nat/bsc_nat_vty.c
@@ -224,27 +224,13 @@
 	return CMD_SUCCESS;
 }
 
-static void parse_reg(void *ctx, regex_t *reg, char **imsi, int argc, const char **argv)
-{
-	if (*imsi) {
-		talloc_free(*imsi);
-		*imsi = NULL;
-	}
-	regfree(reg);
-
-	if (argc > 0) {
-		*imsi = talloc_strdup(ctx, argv[0]);
-		regcomp(reg, argv[0], 0);
-	}
-}
-
 DEFUN(cfg_nat_imsi_allow,
       cfg_nat_imsi_allow_cmd,
       "imsi allow [REGEXP]",
       "Allow matching IMSIs to talk to the MSC. "
       "The defualt is to allow everyone.")
 {
-	parse_reg(_nat, &_nat->imsi_allow_re, &_nat->imsi_allow, argc, argv);
+	bsc_parse_reg(_nat, &_nat->imsi_allow_re, &_nat->imsi_allow, argc, argv);
 	return CMD_SUCCESS;
 }
 
@@ -254,7 +240,7 @@
       "Deny matching IMSIs to talk to the MSC. "
       "The defualt is to not deny.")
 {
-	parse_reg(_nat, &_nat->imsi_deny_re, &_nat->imsi_deny, argc, argv);
+	bsc_parse_reg(_nat, &_nat->imsi_deny_re, &_nat->imsi_deny, argc, argv);
 	return CMD_SUCCESS;
 }
 
@@ -373,7 +359,7 @@
 {
 	struct bsc_config *conf = vty->index;
 
-	parse_reg(conf, &conf->imsi_allow_re, &conf->imsi_allow, argc, argv);
+	bsc_parse_reg(conf, &conf->imsi_allow_re, &conf->imsi_allow, argc, argv);
 	return CMD_SUCCESS;
 }
 
@@ -385,7 +371,7 @@
 {
 	struct bsc_config *conf = vty->index;
 
-	parse_reg(conf, &conf->imsi_deny_re, &conf->imsi_deny, argc, argv);
+	bsc_parse_reg(conf, &conf->imsi_deny_re, &conf->imsi_deny, argc, argv);
 	return CMD_SUCCESS;
 }