diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index a8ce3cc..64fb55b 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -481,16 +481,21 @@
 	OSMO_ASSERT(llist_empty(&state->enabled_tllis));
 }
 
+void gbprox_clear_patch_filter(struct gbproxy_config *cfg)
+{
+	if (cfg->check_imsi) {
+		regfree(&cfg->imsi_re_comp);
+		cfg->check_imsi = 0;
+	}
+}
+
 int gbprox_set_patch_filter(struct gbproxy_config *cfg, const char *filter,
 		const char **err_msg)
 {
 	static char err_buf[300];
 	int rc;
 
-	if (cfg->check_imsi) {
-		regfree(&cfg->imsi_re_comp);
-		cfg->check_imsi = 0;
-	}
+	gbprox_clear_patch_filter(cfg);
 
 	if (!filter)
 		return 0;
diff --git a/openbsc/src/gprs/gb_proxy_vty.c b/openbsc/src/gprs/gb_proxy_vty.c
index ec73ae6..9574a45 100644
--- a/openbsc/src/gprs/gb_proxy_vty.c
+++ b/openbsc/src/gprs/gb_proxy_vty.c
@@ -193,7 +193,7 @@
 		talloc_free(g_cfg->core_apn);
 		g_cfg->core_apn = NULL;
 		g_cfg->core_apn_size = 0;
-		gbprox_set_patch_filter(g_cfg, NULL, NULL);
+		gbprox_clear_patch_filter(g_cfg);
 		return CMD_SUCCESS;
 	}
 
@@ -206,7 +206,7 @@
 	}
 
 	if (!filter) {
-		gbprox_set_patch_filter(g_cfg, NULL, NULL);
+		gbprox_clear_patch_filter(g_cfg);
 	} else if (gbprox_set_patch_filter(g_cfg, filter, &err_msg) != 0) {
 		vty_out(vty, "Match expression invalid: %s%s",
 			err_msg, VTY_NEWLINE);