diff --git a/Marlin/src/Marlin.cpp b/Marlin/src/Marlin.cpp
index 3c85b7308..faf4e6f20 100644
--- a/Marlin/src/Marlin.cpp
+++ b/Marlin/src/Marlin.cpp
@@ -617,9 +617,7 @@ void kill(PGM_P const lcd_msg/*=NULL*/) {
   SERIAL_ERROR_START();
   SERIAL_ERRORLNPGM(MSG_ERR_KILLED);
 
-  #if ENABLED(EXTENSIBLE_UI)
-    UI::onPrinterKilled(lcd_msg ? lcd_msg : PSTR(MSG_KILLED));
-  #elif ENABLED(ULTRA_LCD)
+  #if ENABLED(ULTRA_LCD) || ENABLED(EXTENSIBLE_UI)
     kill_screen(lcd_msg ? lcd_msg : PSTR(MSG_KILLED));
   #else
     UNUSED(lcd_msg);
diff --git a/Marlin/src/lcd/extensible_ui/ui_api.cpp b/Marlin/src/lcd/extensible_ui/ui_api.cpp
index f324f804a..56ac9216f 100644
--- a/Marlin/src/lcd/extensible_ui/ui_api.cpp
+++ b/Marlin/src/lcd/extensible_ui/ui_api.cpp
@@ -1,3 +1,25 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
 /**************
  * ui_api.cpp *
  **************/
@@ -29,6 +51,7 @@
 #include "../../module/probe.h"
 #include "../../module/temperature.h"
 #include "../../libs/duration_t.h"
+#include "../../HAL/shared/Delay.h"
 
 #if DO_SWITCH_EXTRUDER || ENABLED(SWITCHING_NOZZLE) || ENABLED(PARKING_EXTRUDER)
   #include "../../module/tool_change.h"
@@ -64,14 +87,70 @@ inline float clamp(const float value, const float minimum, const float maximum)
   return MAX(MIN(value, maximum), minimum);
 }
 
+static bool printer_killed = false;
+
 namespace UI {
+  #ifdef __SAM3X8E__
+    /**
+     * Implement a special millis() to allow time measurement
+     * within an ISR (such as when the printer is killed).
+     *
+     * To keep proper time, must be called at least every 1s.
+     */
+    uint32_t safe_millis() {
+      // Not killed? Just call millis()
+      if (!printer_killed) return millis();
+
+      static uint32_t currTimeHI = 0; /* Current time */
+
+      // Machine was killed, reinit SysTick so we are able to compute time without ISRs
+      if (currTimeHI == 0) {
+        // Get the last time the Arduino time computed (from CMSIS) and convert it to SysTick
+        currTimeHI = (uint32_t)((GetTickCount() * (uint64_t)(F_CPU/8000)) >> 24);
+
+        // Reinit the SysTick timer to maximize its period
+        SysTick->LOAD  = SysTick_LOAD_RELOAD_Msk;                    // get the full range for the systick timer
+        SysTick->VAL   = 0;                                          // Load the SysTick Counter Value
+        SysTick->CTRL  = // MCLK/8 as source
+                         // No interrupts
+                         SysTick_CTRL_ENABLE_Msk;                    // Enable SysTick Timer
+     }
+
+      // Check if there was a timer overflow from the last read
+      if (SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk) {
+        // There was. This means (SysTick_LOAD_RELOAD_Msk * 1000 * 8)/F_CPU ms has elapsed
+        currTimeHI++;
+      }
+
+      // Calculate current time in milliseconds
+      uint32_t currTimeLO = SysTick_LOAD_RELOAD_Msk - SysTick->VAL; // (in MCLK/8)
+      uint64_t currTime = ((uint64_t)currTimeLO) | (((uint64_t)currTimeHI) << 24);
+
+      // The ms count is
+      return (uint32_t)(currTime / (F_CPU / 8000));
+    }
+
+  #else
+
+    // TODO: Implement for AVR
+    uint32_t safe_millis() { return millis(); }
+
+  #endif
+
+  void delay_us(unsigned long us) {
+    DELAY_US(us);
+  }
 
   void delay_ms(unsigned long ms) {
-    safe_delay(ms);
+    if (printer_killed)
+      DELAY_US(ms * 1000);
+    else
+      safe_delay(ms);
   }
 
   void yield() {
-    thermalManager.manage_heater();
+    if (!printer_killed)
+      thermalManager.manage_heater();
   }
 
   float getActualTemp_celsius(const uint8_t extruder) {
@@ -491,7 +570,7 @@ namespace UI {
   }
 
   const char* FileList::filename() {
-    return IFSD(card.longFilename && card.longFilename[0]) ? card.longFilename : card.filename, "");
+    return IFSD(card.longFilename && card.longFilename[0] ? card.longFilename : card.filename, "");
   }
 
   const char* FileList::shortFilename() {
@@ -603,4 +682,11 @@ void lcd_status_printf_P(const uint8_t level, const char * const fmt, ...) {
   UI::onStatusChanged(buff);
 }
 
+void kill_screen(PGM_P msg) {
+  if (!printer_killed) {
+    printer_killed = true;
+    UI::onPrinterKilled(msg);
+  }
+}
+
 #endif // EXTENSIBLE_UI
diff --git a/Marlin/src/lcd/extensible_ui/ui_api.h b/Marlin/src/lcd/extensible_ui/ui_api.h
index 548706e59..7f72cd523 100644
--- a/Marlin/src/lcd/extensible_ui/ui_api.h
+++ b/Marlin/src/lcd/extensible_ui/ui_api.h
@@ -1,3 +1,25 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
 /************
  * ui_api.h *
  ************/
@@ -127,6 +149,9 @@ namespace UI {
     #endif
   #endif
 
+  // This safe_millis is safe to use even when printer is killed (as long as called at least every 1 second)
+  uint32_t safe_millis();
+  void delay_us(unsigned long us);
   void delay_ms(unsigned long ms);
   void yield(); // Within lengthy loop, call this periodically
 
diff --git a/Marlin/src/lcd/ultralcd.h b/Marlin/src/lcd/ultralcd.h
index b1d9490ec..9f5f5200e 100644
--- a/Marlin/src/lcd/ultralcd.h
+++ b/Marlin/src/lcd/ultralcd.h
@@ -30,6 +30,7 @@
   bool lcd_detected();
   void lcd_update();
   void lcd_setalertstatusPGM(PGM_P message);
+  void kill_screen(PGM_P lcd_msg);
 #else
   inline void lcd_init() {}
   inline bool lcd_detected() { return true; }