diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
index f83289b..4258364 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
@@ -606,8 +606,11 @@
 	}
 }
 
-void bsc_parse_reg(void *ctx, regex_t *reg, char **imsi, int argc, const char **argv)
+int bsc_parse_reg(void *ctx, regex_t *reg, char **imsi, int argc, const char **argv)
 {
+	int ret;
+
+	ret = 0;
 	if (*imsi) {
 		talloc_free(*imsi);
 		*imsi = NULL;
@@ -616,8 +619,16 @@
 
 	if (argc > 0) {
 		*imsi = talloc_strdup(ctx, argv[0]);
-		regcomp(reg, argv[0], 0);
+		ret = regcomp(reg, argv[0], 0);
+
+		/* handle compilation failures */
+		if (ret != 0) {
+			talloc_free(*imsi);
+			*imsi = NULL;
+		}
 	}
+
+	return ret;
 }
 
 static const char *con_types [] = {