diff --git a/lib/MySQL_Session.cpp b/lib/MySQL_Session.cpp
index 15e97c42d..1fa2aa355 100644
--- a/lib/MySQL_Session.cpp
+++ b/lib/MySQL_Session.cpp
@@ -1343,8 +1343,10 @@ __exit_DSS__STATE_NOT_INITIALIZED:
 
 	if (mybe && mybe->server_myds) {
 	if (mybe->server_myds->DSS > STATE_MARIADB_BEGIN && mybe->server_myds->DSS < STATE_MARIADB_END) {
+#ifdef DEBUG
 		MySQL_Data_Stream *myds=mybe->server_myds;
 		MySQL_Connection *myconn=mybe->server_myds->myconn;
+#endif /* DEBUG */
 		proxy_debug(PROXY_DEBUG_MYSQL_CONNECTION, 5, "Sess=%p, status=%d, server_myds->DSS==%d , revents==%d , async_state_machine=%d\n", this, status, mybe->server_myds->DSS, myds->revents, myconn->async_state_machine);
 	} else {
 
diff --git a/lib/MySQL_Thread.cpp b/lib/MySQL_Thread.cpp
index 8cbaa2fe2..62b9e2ca7 100644
--- a/lib/MySQL_Thread.cpp
+++ b/lib/MySQL_Thread.cpp
@@ -1576,7 +1576,9 @@ void MySQL_Thread::run() {
 			if (myds==NULL) {
 				if (mypolls.fds[n].revents) {
 					unsigned char c;
-					read(mypolls.fds[n].fd, &c, 1);	// read just one byte , no need for error handling
+					if (read(mypolls.fds[n].fd, &c, 1)==-1) {// read just one byte
+						proxy_error("Error during read from signal_all_threads()\n");
+					}
 					proxy_debug(PROXY_DEBUG_GENERIC,3, "Got signal from admin , done nothing\n");
 					//fprintf(stderr,"Got signal from admin , done nothing\n"); // FIXME: this is just the scheleton for issue #253
 					if (c) {
@@ -2191,7 +2193,9 @@ void MySQL_Threads_Handler::signal_all_threads(unsigned char _c) {
 	for (i=0;i<num_threads;i++) {
 		MySQL_Thread *thr=(MySQL_Thread *)mysql_threads[i].worker;
 		int fd=thr->pipefd[1];
-		write(fd,&c,1);
+		if (write(fd,&c,1)==-1) {
+			proxy_error("Error during write in signal_all_threads()\n");
+		}
 	}
 }
 
diff --git a/lib/debug.cpp b/lib/debug.cpp
index 2d2e04224..ebf856f9a 100644
--- a/lib/debug.cpp
+++ b/lib/debug.cpp
@@ -9,8 +9,10 @@
 #endif /* DEBUG_EXTERN */
 #endif /* DEBUG */
 
+#ifdef DEBUG
 static unsigned long long pretime=0;
 static spinlock debug_spinlock;
+#endif /* DEBUG */
 
 static inline unsigned long long debug_monotonic_time() {
 	struct timespec ts;
diff --git a/lib/mysql_connection.cpp b/lib/mysql_connection.cpp
index 535ae652c..d31b4e28b 100644
--- a/lib/mysql_connection.cpp
+++ b/lib/mysql_connection.cpp
@@ -701,7 +701,9 @@ handler_again:
 
 
 void MySQL_Connection::next_event(MDB_ASYNC_ST new_st) {
+#ifdef DEBUG
 	int fd;
+#endif /* DEBUG */
 	wait_events=0;
 
 	if (async_exit_status & MYSQL_WAIT_READ)
@@ -709,9 +711,15 @@ void MySQL_Connection::next_event(MDB_ASYNC_ST new_st) {
 	if (async_exit_status & MYSQL_WAIT_WRITE)
 		wait_events|= POLLOUT;
 	if (wait_events)
+#ifdef DEBUG
 		fd= mysql_get_socket(mysql);
+#else
+		mysql_get_socket(mysql);
+#endif /* DEBUG */
 	else
+#ifdef DEBUG
 		fd= -1;
+#endif /* DEBUG */
 	if (async_exit_status & MYSQL_WAIT_TIMEOUT) {
 	timeout=10000;
 	//tv.tv_sec= 0;