diff --git a/openbsc/tests/bsc-nat/bsc_nat_test.c b/openbsc/tests/bsc-nat/bsc_nat_test.c
index 10b876b..def6bfe 100644
--- a/openbsc/tests/bsc-nat/bsc_nat_test.c
+++ b/openbsc/tests/bsc-nat/bsc_nat_test.c
@@ -425,20 +425,18 @@
 static void test_mgcp_rewrite(void)
 {
 	int i;
-	struct msgb *input, *output;
+	struct msgb *output;
 	fprintf(stderr, "Test rewriting MGCP messages.\n");
 
-	input = msgb_alloc(4096, "input");
-
 	for (i = 0; i < ARRAY_SIZE(mgcp_messages); ++i) {
 		const char *orig = mgcp_messages[i].orig;
 		const char *patc = mgcp_messages[i].patch;
 		const char *ip = mgcp_messages[i].ip;
 		const int port = mgcp_messages[i].port;
 
-		copy_to_msg(input, (const u_int8_t *) orig, strlen(orig) + 1);
+		char *input = strdup(orig);
 
-		output = bsc_mgcp_rewrite(input, ip, port);
+		output = bsc_mgcp_rewrite(input, strlen(input), ip, port);
 		if (msgb_l2len(output) != strlen(patc)) {
 			fprintf(stderr, "Wrong sizes for test: %d  %d != %d != %d\n", i, msgb_l2len(output), strlen(patc), strlen(orig));
 			fprintf(stderr, "String '%s' vs '%s'\n", (const char *) output->l2h, patc);
@@ -451,9 +449,8 @@
 		}
 
 		msgb_free(output);
+		free(input);
 	}
-
-	msgb_free(input);
 }
 
 static void test_mgcp_parse(void)