diff --git a/Makefile b/Makefile
index c39ae36..54937ce 100644
--- a/Makefile
+++ b/Makefile
@@ -50,3 +50,5 @@ setup: $(ARDUINO_DIR)/arduino-cli
 	$(ARDUINO_CLI) core update-index
 	$(ARDUINO_CLI) core install $(CORES)
 	$(ARDUINO_CLI) core list
+
+.PHONY: clean %.hex all setup
diff --git a/src/BasicStepperDriver.cpp b/src/BasicStepperDriver.cpp
index c296eba..4ccec48 100644
--- a/src/BasicStepperDriver.cpp
+++ b/src/BasicStepperDriver.cpp
@@ -138,7 +138,7 @@ void BasicStepperDriver::startMove(long steps, long time){
             float a2 = 1.0 / profile.accel + 1.0 / profile.decel;
             float sqrt_candidate = t*t - 2 * a2 * d;  // in √b^2-4ac
             if (sqrt_candidate >= 0){
-                speed = min(speed, (t - sqrt(sqrt_candidate)) / a2);
+                speed = min(speed, (t - (float)sqrt(sqrt_candidate)) / a2);
             };
         }
         // how many microsteps from 0 to target speed
diff --git a/src/MultiDriver.cpp b/src/MultiDriver.cpp
index 7ea00b1..92789f5 100644
--- a/src/MultiDriver.cpp
+++ b/src/MultiDriver.cpp
@@ -67,7 +67,7 @@ long MultiDriver::nextAction(void){
  */
 void MultiDriver::startBrake(void){
     FOREACH_MOTOR(
-        if (event_timers[i] >= 0){
+        if (event_timers[i] > 0){
             motors[i]->startBrake();
         }
     )
@@ -91,10 +91,9 @@ bool MultiDriver::isRunning(void){
  * positive to move forward, negative to reverse, 0 to remain still
  */
 void MultiDriver::move(long steps1, long steps2, long steps3){
-    unsigned long next_event;
     startMove(steps1, steps2, steps3);
     while (!ready){
-        next_event = nextAction();
+        nextAction();
     }
 }
 
diff --git a/src/MultiDriver.h b/src/MultiDriver.h
index 97ec61b..07e4e54 100644
--- a/src/MultiDriver.h
+++ b/src/MultiDriver.h
@@ -36,7 +36,7 @@ class MultiDriver {
     // ready to start a new move
     bool ready = true;
     // when next state change is due for each motor
-    long event_timers[MAX_MOTORS];
+    unsigned long event_timers[MAX_MOTORS];
     unsigned long next_action_interval = 0;
     unsigned long last_action_end = 0;
 
diff --git a/src/SyncDriver.cpp b/src/SyncDriver.cpp
index d562b2c..527dd61 100644
--- a/src/SyncDriver.cpp
+++ b/src/SyncDriver.cpp
@@ -16,14 +16,12 @@
  */
 void SyncDriver::startMove(long steps1, long steps2, long steps3){
     long steps[3] = {steps1, steps2, steps3};
-    long timing[MAX_MOTORS];
     /*
      * find which motor would take the longest to finish,
      */
     long move_time = 0;
     FOREACH_MOTOR(
         long m = motors[i]->getTimeForMove(abs(steps[i]));
-        timing[i] = m;
         if (m > move_time){
             move_time = m;
         }