diff --git a/src/delete-carddav-object.c b/src/delete-carddav-object.c
index 4e3a603..f790965 100644
--- a/src/delete-carddav-object.c
+++ b/src/delete-carddav-object.c
@@ -217,13 +217,16 @@ gboolean carddav_delete(carddav_settings* settings, carddav_error* error) {
 					 * hoping for the best.
 					 */
 					else if (lock_error.code == 501) {
-						lock_token = g_strdup("");
+						lock_error.code = 0;
+						g_free(lock_error.str);
+						lock_error.str = NULL;
+						LOCKSUPPORT = FALSE;
 					}
 					else {
 						lock = -1;
 					}
 				}
-				if (! LOCKSUPPORT || (LOCKSUPPORT && lock_token && lock_error.code != 423)) {
+				if (lock == 0) {
 					curl_easy_setopt(curl, CURLOPT_HTTPHEADER, http_header);
 					curl_easy_setopt(curl, CURLOPT_URL, rebuild_url(settings, url));
 					curl_easy_setopt(curl, CURLOPT_POSTFIELDS, NULL);
@@ -233,7 +236,7 @@ gboolean carddav_delete(carddav_settings* settings, carddav_error* error) {
 					curl_easy_setopt(curl, CURLOPT_UNRESTRICTED_AUTH, 1);
 					curl_easy_setopt(curl, CURLOPT_POSTREDIR, CURL_REDIR_POST_ALL);
 					res = curl_easy_perform(curl);
-					if (LOCKSUPPORT && lock_token) {
+					if (LOCKSUPPORT) {
 						carddav_unlock_object(
 								lock_token, url, settings, &lock_error);
 					}
@@ -402,13 +405,16 @@ gboolean carddav_delete_by_uri(carddav_settings* settings, carddav_error* error)
 				* hoping for the best.
 				*/
 			else if (lock_error.code == 501) {
-				lock_token = g_strdup("");
+				lock_error.code = 0;
+				g_free(lock_error.str);
+				lock_error.str = NULL;
+				LOCKSUPPORT = FALSE;
 			}
 			else {
 				lock = -1;
 			}
 		}
-		if (! LOCKSUPPORT || (LOCKSUPPORT && lock_token && lock_error.code != 423)) {
+		if (lock == 0) {
 			curl_easy_setopt(curl, CURLOPT_HTTPHEADER, http_header);
 			curl_easy_setopt(curl, CURLOPT_URL, rebuild_url(settings, url));
 			curl_easy_setopt(curl, CURLOPT_POSTFIELDS, NULL);
@@ -418,7 +424,7 @@ gboolean carddav_delete_by_uri(carddav_settings* settings, carddav_error* error)
 			curl_easy_setopt(curl, CURLOPT_UNRESTRICTED_AUTH, 1);
 			curl_easy_setopt(curl, CURLOPT_POSTREDIR, CURL_REDIR_POST_ALL);
 			res = curl_easy_perform(curl);
-			if (LOCKSUPPORT && lock_token) {
+			if (LOCKSUPPORT) {
 				carddav_unlock_object(
 						lock_token, url, settings, &lock_error);
 			}
diff --git a/src/modify-carddav-object.c b/src/modify-carddav-object.c
index 6c97ed3..30015d6 100644
--- a/src/modify-carddav-object.c
+++ b/src/modify-carddav-object.c
@@ -217,13 +217,16 @@ gboolean carddav_modify(carddav_settings* settings, carddav_error* error) {
 						 * hoping for the best.
 						 */
 						else if (lock_error.code == 501) {
-							lock_token = g_strdup("");
+							lock_error.code = 0;
+							g_free(lock_error.str);
+							lock_error.str = NULL;
+							LOCKSUPPORT = FALSE;
 						}
 						else {
 							lock = -1;
 						}
 					}
-					if (! LOCKSUPPORT || (LOCKSUPPORT && lock_token && lock_error.code != 423)) {
+					if (lock == 0) {
 						curl_easy_setopt(curl, CURLOPT_HTTPHEADER, http_header);
 						curl_easy_setopt(curl, CURLOPT_URL, rebuild_url(settings, url));
 						curl_easy_setopt(curl, CURLOPT_POSTFIELDS, settings->file);
@@ -234,7 +237,7 @@ gboolean carddav_modify(carddav_settings* settings, carddav_error* error) {
 						curl_easy_setopt(curl, CURLOPT_POSTREDIR, CURL_REDIR_POST_ALL);
 						curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "PUT");
 						res = curl_easy_perform(curl);
-						if (LOCKSUPPORT && lock_token) {
+						if (LOCKSUPPORT) {
 							carddav_unlock_object(
 									lock_token, url, settings, &lock_error);
 						}
@@ -415,13 +418,13 @@ gboolean carddav_modify_by_uri(carddav_settings* settings, carddav_error* error)
 					* hoping for the best.
 					*/
 				else if (lock_error.code == 501) {
-					lock_token = g_strdup("");
+					LOCKSUPPORT = FALSE;
 				}
 				else {
 					lock = -1;
 				}
 			}
-			if (! LOCKSUPPORT || (LOCKSUPPORT && lock_token && lock_error.code != 423)) {
+			if (lock == 0) {
 				curl_easy_setopt(curl, CURLOPT_HTTPHEADER, http_header);
 				curl_easy_setopt(curl, CURLOPT_URL, rebuild_url(settings, url));
 				curl_easy_setopt(curl, CURLOPT_POSTFIELDS, settings->file);
@@ -432,7 +435,7 @@ gboolean carddav_modify_by_uri(carddav_settings* settings, carddav_error* error)
 				curl_easy_setopt(curl, CURLOPT_POSTREDIR, CURL_REDIR_POST_ALL);
 				curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "PUT");
 				res = curl_easy_perform(curl);
-				if (LOCKSUPPORT && lock_token) {
+				if (LOCKSUPPORT) {
 					carddav_unlock_object(
 							lock_token, url, settings, &lock_error);
 				}