diff --git a/klippy/mcu.py b/klippy/mcu.py
index 4fa7772b..3fda90dc 100644
--- a/klippy/mcu.py
+++ b/klippy/mcu.py
@@ -257,13 +257,15 @@ class MCU_digital_out:
         if self._max_duration and self._start_value != self._shutdown_value:
             raise pins.error("Pin with max duration must have start"
                              " value equal to shutdown value")
+        mdur_ticks = self._mcu.seconds_to_clock(self._max_duration)
+        if mdur_ticks >= 1<<31:
+            raise pins.error("Digital pin max duration too large")
         self._mcu.request_move_queue_slot()
         self._oid = self._mcu.create_oid()
         self._mcu.add_config_cmd(
             "config_digital_out oid=%d pin=%s value=%d default_value=%d"
-            " max_duration=%d"
-            % (self._oid, self._pin, self._start_value, self._shutdown_value,
-               self._mcu.seconds_to_clock(self._max_duration)))
+            " max_duration=%d" % (self._oid, self._pin, self._start_value,
+                                  self._shutdown_value, mdur_ticks))
         self._mcu.add_config_cmd("update_digital_out oid=%d value=%d"
                                  % (self._oid, self._start_value),
                                  on_restart=True)
@@ -316,6 +318,9 @@ class MCU_pwm:
         printtime = self._mcu.estimated_print_time(curtime)
         self._last_clock = self._mcu.print_time_to_clock(printtime + 0.200)
         cycle_ticks = self._mcu.seconds_to_clock(self._cycle_time)
+        mdur_ticks = self._mcu.seconds_to_clock(self._max_duration)
+        if mdur_ticks >= 1<<31:
+            raise pins.error("PWM pin max duration too large")
         if self._hardware_pwm:
             self._pwm_max = self._mcu.get_constant_float("PWM_MAX")
             if self._is_static:
@@ -331,8 +336,7 @@ class MCU_pwm:
                 " default_value=%d max_duration=%d"
                 % (self._oid, self._pin, cycle_ticks,
                    self._start_value * self._pwm_max,
-                   self._shutdown_value * self._pwm_max,
-                   self._mcu.seconds_to_clock(self._max_duration)))
+                   self._shutdown_value * self._pwm_max, mdur_ticks))
             svalue = int(self._start_value * self._pwm_max + 0.5)
             self._mcu.add_config_cmd("queue_pwm_out oid=%d clock=%d value=%d"
                                      % (self._oid, self._last_clock, svalue),
@@ -347,14 +351,15 @@ class MCU_pwm:
             self._mcu.add_config_cmd("set_digital_out pin=%s value=%d"
                                      % (self._pin, self._start_value >= 0.5))
             return
+        if cycle_ticks >= 1<<31:
+            raise pins.error("PWM pin cycle time too large")
         self._mcu.request_move_queue_slot()
         self._oid = self._mcu.create_oid()
         self._mcu.add_config_cmd(
             "config_digital_out oid=%d pin=%s value=%d"
             " default_value=%d max_duration=%d"
             % (self._oid, self._pin, self._start_value >= 1.0,
-               self._shutdown_value >= 0.5,
-               self._mcu.seconds_to_clock(self._max_duration)))
+               self._shutdown_value >= 0.5, mdur_ticks))
         self._mcu.add_config_cmd(
             "set_digital_out_pwm_cycle oid=%d cycle_ticks=%d"
             % (self._oid, cycle_ticks))
@@ -383,6 +388,9 @@ class MCU_pwm:
             cycle_time = self._cycle_time
         cycle_ticks = self._mcu.seconds_to_clock(cycle_time)
         if cycle_ticks != self._last_cycle_ticks:
+            if cycle_ticks >= 1<<31:
+                raise self._mcu.get_printer().command_error(
+                    "PWM cycle time too large")
             self._set_cycle_ticks.send([self._oid, cycle_ticks],
                                        minclock=minclock, reqclock=clock)
             self._last_cycle_ticks = cycle_ticks