diff --git a/main.c b/main.c
index 8dc8c17..008f30e 100644
--- a/main.c
+++ b/main.c
@@ -78,8 +78,8 @@ static MUTEX_DECL(mutex);
 static int32_t frequency_offset = 5000;
 static uint32_t frequency = 10000000;
 static int8_t drive_strength = DRIVE_STRENGTH_AUTO;
-int8_t sweep_enabled = TRUE;
-volatile int8_t sweep_once = FALSE;
+int8_t sweep_mode = SWEEP_ENABLE;
+
 volatile uint8_t redraw_request = 0; // contains REDRAW_XXX flags
 int16_t vbat = 0;
 
@@ -91,10 +91,10 @@ static THD_FUNCTION(Thread1, arg)
 
   while (1) {
     bool completed = false;
-    if (sweep_enabled || sweep_once) {
+    if (sweep_mode&(SWEEP_ENABLE|SWEEP_ONCE)) {
       chMtxLock(&mutex);
       completed = sweep(true);
-      sweep_once = FALSE;
+      sweep_mode&=~SWEEP_ONCE;
       chMtxUnlock(&mutex);
     } else {
       __WFI();
@@ -103,7 +103,7 @@ static THD_FUNCTION(Thread1, arg)
     chMtxLock(&mutex);
     ui_process();
 
-    if (sweep_enabled) {
+    if (sweep_mode&SWEEP_ENABLE) {
       if (vbat != -1) {
         adc_stop(ADC1);
         vbat = adc_vbat_read(ADC1);
@@ -136,19 +136,19 @@ static THD_FUNCTION(Thread1, arg)
 static inline void
 pause_sweep(void)
 {
-  sweep_enabled = FALSE;
+  sweep_mode&=~SWEEP_ENABLE;
 }
 
 static inline void
 resume_sweep(void)
 {
-  sweep_enabled = TRUE;
+  sweep_mode|=SWEEP_ENABLE;
 }
 
 void
 toggle_sweep(void)
 {
-  sweep_enabled = !sweep_enabled;
+  sweep_mode^=SWEEP_ENABLE;
 }
 
 static float
@@ -842,11 +842,11 @@ VNA_SHELL_FUNCTION(cmd_scan)
   if (cal_auto_interpolate && (cal_status & CALSTAT_APPLY))
     cal_interpolate(lastsaveid);
 
-  sweep_once = TRUE;
+  sweep_mode|= SWEEP_ONCE;
   chMtxUnlock(&mutex);
 
   // wait finishing sweep
-  while (sweep_once)
+  while (sweep_mode&SWEEP_ONCE)
     chThdSleepMilliseconds(10);
 }
 
diff --git a/nanovna.h b/nanovna.h
index b79d4c8..f2b9721 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -86,7 +86,9 @@ double my_atof(const char *p);
 void toggle_sweep(void);
 void loadDefaultProps(void);
 
-extern int8_t sweep_enabled;
+#define SWEEP_ENABLE  0x01
+#define SWEEP_ONCE    0x02
+extern int8_t sweep_mode;
 
 /*
  * dsp.c
diff --git a/ui.c b/ui.c
index eaffa8d..93cc96d 100644
--- a/ui.c
+++ b/ui.c
@@ -1358,7 +1358,7 @@ menu_item_modify_attribute(const menuitem_t *menu, int item,
       *fg = config.menu_normal_color;
     }
   } else if (menu == menu_stimulus) {
-    if (item == 5 /* PAUSE */ && !sweep_enabled) {
+    if (item == 5 /* PAUSE */ && !(sweep_mode&SWEEP_ENABLE)) {
       *bg = DEFAULT_MENU_TEXT_COLOR;
       *fg = config.menu_normal_color;
     }