diff --git a/clock.c b/clock.c
index d0868c2..db62ae4 100644
--- a/clock.c
+++ b/clock.c
@@ -35,7 +35,7 @@ void clock_250ms() {
 		SREG = save_reg;
 	}
 
-	ifclock(CLOCK_FLAG_1S) {
+	ifclock(clock_flag_1s) {
 		if (debug_flags & DEBUG_POSITION) {
 			// current position
 			sersendf_P(PSTR("Pos: %ld,%ld,%ld,%ld,%lu\n"), current_position.X, current_position.Y, current_position.Z, current_position.E, current_position.F);
@@ -68,7 +68,7 @@ void clock_10ms() {
 
 	temp_tick();
 
-	ifclock(CLOCK_FLAG_250MS) {
+	ifclock(clock_flag_250ms) {
 		clock_250ms();
 	}
 
diff --git a/dda_queue.c b/dda_queue.c
index 8a37ae1..0d649a6 100644
--- a/dda_queue.c
+++ b/dda_queue.c
@@ -168,7 +168,7 @@ void queue_flush() {
 /// waits for a space in the queue to become available
 void queue_wait() {
 	for (;queue_empty() == 0;) {
-		ifclock(CLOCK_FLAG_10MS) {
+		ifclock(clock_flag_10ms) {
 			clock_10ms();
 		}
 	}
diff --git a/gcode_process.c b/gcode_process.c
index 098a978..4c69f47 100644
--- a/gcode_process.c
+++ b/gcode_process.c
@@ -158,7 +158,7 @@ void process_gcode_command() {
 				queue_wait();
 				// delay
 				for (;next_target.P > 0;next_target.P--) {
-					ifclock(CLOCK_FLAG_10MS) {
+					ifclock(clock_flag_10ms) {
 						clock_10ms();
 					}
 					delay_ms(1);
diff --git a/mendel.c b/mendel.c
index 2dab42b..8249b68 100644
--- a/mendel.c
+++ b/mendel.c
@@ -262,7 +262,7 @@ int main (void)
 			gcode_parse_char(c);
 		}
 
-		ifclock(CLOCK_FLAG_10MS) {
+		ifclock(clock_flag_10ms) {
 			clock_10ms();
 		}
 	}
diff --git a/timer.c b/timer.c
index 390b082..1c1244a 100644
--- a/timer.c
+++ b/timer.c
@@ -33,8 +33,11 @@ uint8_t						clock_counter_10ms = 0;
 uint8_t						clock_counter_250ms = 0;
 /// keep track of when 1s has elapsed
 uint8_t						clock_counter_1s = 0;
+
 /// flags to tell main loop when above have elapsed
-volatile uint8_t	clock_flag = 0;
+volatile uint8_t	clock_flag_10ms = 0;
+volatile uint8_t	clock_flag_250ms = 0;
+volatile uint8_t	clock_flag_1s = 0;
 
 /// comparator B is the system clock, happens every TICK_TIME
 ISR(TIMER1_COMPB_vect) {
@@ -47,17 +50,17 @@ ISR(TIMER1_COMPB_vect) {
 	clock_counter_10ms += TICK_TIME_MS;
 	if (clock_counter_10ms >= 10) {
 		clock_counter_10ms -= 10;
-		clock_flag |= CLOCK_FLAG_10MS;
+		clock_flag_10ms = 1;
 
 		clock_counter_250ms += 1;
 		if (clock_counter_250ms >= 25) {
 			clock_counter_250ms -= 25;
-			clock_flag |= CLOCK_FLAG_250MS;
+			clock_flag_250ms = 1;
 
 			clock_counter_1s += 1;
 			if (clock_counter_1s >= 4) {
 				clock_counter_1s -= 4;
-				clock_flag |= CLOCK_FLAG_1S;
+				clock_flag_1s = 1;
 			}
 		}
 	}
diff --git a/timer.h b/timer.h
index dd6b6be..9edc71b 100644
--- a/timer.h
+++ b/timer.h
@@ -11,12 +11,13 @@
 /*
 clock stuff
 */
-extern volatile uint8_t	clock_flag;
+extern volatile uint8_t	clock_flag_10ms;
+extern volatile uint8_t	clock_flag_250ms;
+extern volatile uint8_t	clock_flag_1s;
 
-#define	CLOCK_FLAG_10MS								1
-#define	CLOCK_FLAG_250MS							2
-#define	CLOCK_FLAG_1S									4
-#define	ifclock(F)	for (;clock_flag & (F);clock_flag &= ~(F))
+// If the specific bit is set, execute the following block exactly once
+// and then clear the flag.
+#define	ifclock(F)	for (;F;F=0 )
 
 /*
 timer stuff