diff --git a/channels/chan_h323.c b/channels/chan_h323.c
index 70761d8836..afecf0f3db 100755
--- a/channels/chan_h323.c
+++ b/channels/chan_h323.c
@@ -1271,7 +1271,7 @@ static int restart_monitor(void)
 		ast_log(LOG_WARNING, "Cannot kill myself\n");
 		return -1;
 	}
-	if (monitor_thread && (monitor_thread != AST_PTHREADT_STOP)) {
+	if (monitor_thread && (monitor_thread != AST_PTHREADT_NULL)) {
 		/* Wake up the thread */
 		pthread_kill(monitor_thread, SIGURG);
 	} else {
diff --git a/channels/chan_mgcp.c b/channels/chan_mgcp.c
index 1554b33655..f1fa9dec8a 100755
--- a/channels/chan_mgcp.c
+++ b/channels/chan_mgcp.c
@@ -2569,7 +2569,7 @@ static int restart_monitor(void)
 		ast_log(LOG_WARNING, "Cannot kill myself\n");
 		return -1;
 	}
-	if (monitor_thread) {
+	if (monitor_thread != AST_PTHREADT_NULL) {
 		/* Wake up the thread */
 		pthread_kill(monitor_thread, SIGURG);
 	} else {
diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index bcf9ff9a26..7af447007c 100755
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -5829,7 +5829,7 @@ static int restart_monitor(void)
 		ast_log(LOG_WARNING, "Cannot kill myself\n");
 		return -1;
 	}
-	if (monitor_thread) {
+	if (monitor_thread != AST_PTHREADT_NULL) {
 		/* Wake up the thread */
 		pthread_kill(monitor_thread, SIGURG);
 	} else {
diff --git a/channels/chan_skinny.c b/channels/chan_skinny.c
index 0a01bdc577..cccb8429cd 100755
--- a/channels/chan_skinny.c
+++ b/channels/chan_skinny.c
@@ -2426,7 +2426,7 @@ static int restart_monitor(void)
 		ast_log(LOG_WARNING, "Cannot kill myself\n");
 		return -1;
 	}
-	if (monitor_thread) {
+	if (monitor_thread != AST_PTHREADT_NULL) {
 		/* Wake up the thread */
 		pthread_kill(monitor_thread, SIGURG);
 	} else {
diff --git a/channels/chan_vofr.c b/channels/chan_vofr.c
index 3d677bd3d4..444701fd7d 100755
--- a/channels/chan_vofr.c
+++ b/channels/chan_vofr.c
@@ -1008,7 +1008,7 @@ static int restart_monitor(void)
 		ast_log(LOG_WARNING, "Cannot kill myself\n");
 		return -1;
 	}
-	if (monitor_thread) {
+	if (monitor_thread != AST_PTHREADT_NULL) {
 		/* Wake up the thread */
 		pthread_kill(monitor_thread, SIGURG);
 	} else {
diff --git a/channels/chan_zap.c b/channels/chan_zap.c
index 930a870fca..48675db0a0 100755
--- a/channels/chan_zap.c
+++ b/channels/chan_zap.c
@@ -5182,7 +5182,7 @@ static int restart_monitor(void)
 		ast_log(LOG_WARNING, "Cannot kill myself\n");
 		return -1;
 	}
-	if (monitor_thread) {
+	if (monitor_thread != AST_PTHREADT_NULL) {
 		/* Just signal it to be sure it wakes up */
 #if 0
 		pthread_cancel(monitor_thread);