diff --git a/cmd/cmd.c b/cmd/cmd.c
index 291939a..f1a7da9 100644
--- a/cmd/cmd.c
+++ b/cmd/cmd.c
@@ -8,7 +8,7 @@
 #include "uart.h"
 
 #ifdef CMD_DBG
-#define DBG(format, ...) os_printf(format, ## __VA_ARGS__)
+#define DBG(format, ...) do { os_printf(format, ## __VA_ARGS__) } while(0)
 #else
 #define DBG(format, ...) do { } while(0)
 #endif
diff --git a/cmd/handlers.c b/cmd/handlers.c
index 5baf821..35d19ee 100644
--- a/cmd/handlers.c
+++ b/cmd/handlers.c
@@ -13,7 +13,7 @@
 #endif
 
 #ifdef CMD_DBG
-#define DBG(format, ...) os_printf(format, ## __VA_ARGS__)
+#define DBG(format, ...) do { os_printf(format, ## __VA_ARGS__) } while(0)
 #else
 #define DBG(format, ...) do { } while(0)
 #endif
diff --git a/esp-link/cgioptiboot.c b/esp-link/cgioptiboot.c
index 47cdea2..c266014 100644
--- a/esp-link/cgioptiboot.c
+++ b/esp-link/cgioptiboot.c
@@ -16,10 +16,8 @@
 #define PGM_TIMEOUT  20000   // timeout when sync is achieved, in milliseconds
 #define PGM_INTERVAL   200   // send sync at this interval in ms when in programming mode
 
-#define OPTIBOOT_DBG
-#undef DBG
 #ifdef OPTIBOOT_DBG
-#define DBG(format, ...) os_printf(format, ## __VA_ARGS__)
+#define DBG(format, ...) do { os_printf(format, ## __VA_ARGS__) } while(0)
 #else
 #define DBG(format, ...) do { } while(0)
 #endif
diff --git a/esp-link/cgiwifi.c b/esp-link/cgiwifi.c
index 5297e54..1b7f71c 100644
--- a/esp-link/cgiwifi.c
+++ b/esp-link/cgiwifi.c
@@ -23,7 +23,7 @@ Cgi/template routines for the /wifi url.
 #include "mdns.h"
 
 #ifdef CGIWIFI_DBG
-#define DBG(format, ...) os_printf(format, ## __VA_ARGS__)
+#define DBG(format, ...) do { os_printf(format, ## __VA_ARGS__) } while(0)
 #else
 #define DBG(format, ...) do { } while(0)
 #endif
diff --git a/esp-link/mdns.c b/esp-link/mdns.c
index 9455ce8..a6039bb 100644
--- a/esp-link/mdns.c
+++ b/esp-link/mdns.c
@@ -13,7 +13,7 @@
 #include "mdns.h"
 
 #ifdef MDNS_DBG
-#define DBG(format, ...) os_printf(format, ## __VA_ARGS__)
+#define DBG(format, ...) do { os_printf(format, ## __VA_ARGS__) } while(0)
 #else
 #define DBG(format, ...) do { } while(0)
 #endif
diff --git a/httpd/httpd.c b/httpd/httpd.c
index f56e579..e9fa6c5 100644
--- a/httpd/httpd.c
+++ b/httpd/httpd.c
@@ -18,7 +18,7 @@ Esp8266 http server - core routines
 #include "httpd.h"
 
 #ifdef HTTPD_DBG
-#define DBG(format, ...) os_printf(format, ## __VA_ARGS__)
+#define DBG(format, ...) do { os_printf(format, ## __VA_ARGS__) } while(0)
 #else
 #define DBG(format, ...) do { } while(0)
 #endif
diff --git a/include/user_config.h b/include/user_config.h
index 02c0a0c..853dc8a 100644
--- a/include/user_config.h
+++ b/include/user_config.h
@@ -30,6 +30,7 @@
 #undef SLIP_DBG
 #define UART_DBG
 #define MDNS_DBG
+#define OPTIBOOT_DBG
 
 // If defined, the default hostname for DHCP will include the chip ID to make it unique
 #undef CHIP_IN_HOSTNAME
diff --git a/mqtt/mqtt_cmd.c b/mqtt/mqtt_cmd.c
index 3cca79b..0d7e65a 100644
--- a/mqtt/mqtt_cmd.c
+++ b/mqtt/mqtt_cmd.c
@@ -8,7 +8,7 @@
 #include "mqtt_cmd.h"
 
 #ifdef MQTTCMD_DBG
-#define DBG(format, ...) os_printf(format, ## __VA_ARGS__)
+#define DBG(format, ...) do { os_printf(format, ## __VA_ARGS__) } while(0)
 #else
 #define DBG(format, ...) do { } while(0)
 #endif
diff --git a/serial/slip.c b/serial/slip.c
index b9446e3..866c811 100644
--- a/serial/slip.c
+++ b/serial/slip.c
@@ -8,7 +8,7 @@
 #include "cmd.h"
 
 #ifdef SLIP_DBG
-#define DBG(format, ...) os_printf(format, ## __VA_ARGS__)
+#define DBG(format, ...) do { os_printf(format, ## __VA_ARGS__) } while(0)
 #else
 #define DBG(format, ...) do { } while(0)
 #endif