diff --git a/core/platform/lf_arduino_support.c b/core/platform/lf_arduino_support.c
index 0e5d276f3..3659caa22 100644
--- a/core/platform/lf_arduino_support.c
+++ b/core/platform/lf_arduino_support.c
@@ -133,14 +133,17 @@ int lf_clock_gettime(instant_t* t) {
  * nested critical sections.
 */
 int lf_critical_section_enter() { 
-    _lf_num_nested_critical_sections++;
-    // if (_lf_num_nested_critical_sections++ == 0) {
-    //     // First nested entry into a critical section.
-    //     // If interrupts are not initially enabled, then increment again to prevent
-    //     // TODO: Do we need to check whether the interrupts were enabled to
-    //     //  begin with? AFAIK there is no Arduino API for that 
-    //     noInterrupts();
-    // }
+    if (_lf_num_nested_critical_sections++ == 0) {
+        // First nested entry into a critical section.
+        // If interrupts are not initially enabled, then increment again to prevent
+        // TODO: Do we need to check whether the interrupts were enabled to
+        //  begin with? AFAIK there is no Arduino API for that 
+        #if BOARD==MBED
+            core_util_critical_section_enter(); //MBED Boards use an RTOS, so we use a specific call to enter a critical section.
+        #else
+            noInterrupts();
+        #endif
+    }
     return 0;
 }
 
@@ -158,10 +161,13 @@ int lf_critical_section_exit() {
     if (_lf_num_nested_critical_sections <= 0) {
         return 1;
     }
-    // if (--_lf_num_nested_critical_sections == 0) {
-    //     interrupts();
-    // }
-    --_lf_num_nested_critical_sections;
+    if (--_lf_num_nested_critical_sections == 0) {
+        #if BOARD==MBED
+            core_util_critical_section_exit(); //MBED Boards use an RTOS, so we use a specific call to exit a critical section.
+        #else
+            interrupts();
+        #endif
+    }
     return 0;
 }
 
diff --git a/include/core/platform/lf_arduino_support.h b/include/core/platform/lf_arduino_support.h
index a8a7f9e8a..ea3986ef5 100644
--- a/include/core/platform/lf_arduino_support.h
+++ b/include/core/platform/lf_arduino_support.h
@@ -36,57 +36,65 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <time.h>   // For CLOCK_MONOTONIC
 #include <stdbool.h>
 
+#define AVR 0
+#define megaAVR 1
+#define SAMD 2
+#define SAM 3
+#define MBED 4
+
 #ifndef BOARD
-#if defined(ARDUINO_AVR_ADK)       
-    #define BOARD "Mega Adk"
+#if defined(ARDUINO_AVR_ADK)
+    #define BOARD AVR
 #elif defined(ARDUINO_AVR_BT)    // Bluetooth
-    #define BOARD "Bt"
-#elif defined(ARDUINO_AVR_DUEMILANOVE)       
-    #define BOARD "Duemilanove"
-#elif defined(ARDUINO_AVR_ESPLORA)       
-    #define BOARD "Esplora"
-#elif defined(ARDUINO_AVR_ETHERNET)       
-    #define BOARD "Ethernet"
-#elif defined(ARDUINO_AVR_FIO)       
-    #define BOARD "Fio"
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_DUEMILANOVE)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_ESPLORA)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_ETHERNET)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_FIO)      
+    #define BOARD AVR
 #elif defined(ARDUINO_AVR_GEMMA)
-    #define BOARD "Gemma"
-#elif defined(ARDUINO_AVR_LEONARDO)       
-    #define BOARD "Leonardo"
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_LEONARDO)
+    #define BOARD AVR
 #elif defined(ARDUINO_AVR_LILYPAD)
-    #define BOARD "Lilypad"
+    #define BOARD AVR
 #elif defined(ARDUINO_AVR_LILYPAD_USB)
-    #define BOARD "Lilypad Usb"
-#elif defined(ARDUINO_AVR_MEGA)       
-    #define BOARD "Mega"
-#elif defined(ARDUINO_AVR_MEGA2560)       
-    #define BOARD "Mega 2560"
-#elif defined(ARDUINO_AVR_MICRO)       
-    #define BOARD "Micro"
-#elif defined(ARDUINO_AVR_MINI)       
-    #define BOARD "Mini"
-#elif defined(ARDUINO_AVR_NANO)       
-    #define BOARD "Nano"
-#elif defined(ARDUINO_AVR_NG)       
-    #define BOARD "NG"
-#elif defined(ARDUINO_AVR_PRO)       
-    #define BOARD "Pro"
-#elif defined(ARDUINO_AVR_ROBOT_CONTROL)       
-    #define BOARD "Robot Ctrl"
-#elif defined(ARDUINO_AVR_ROBOT_MOTOR)       
-    #define BOARD "Robot Motor"
-#elif defined(ARDUINO_AVR_UNO) || defined(__AVR_ATmega4809__)       
-    #define BOARD "Uno"
-#elif defined(ARDUINO_AVR_YUN)       
-    #define BOARD "Yun"
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_MEGA)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_MEGA2560)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_MICRO)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_MINI)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_NANO)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_NG)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_PRO)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_ROBOT_CONTROL)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_ROBOT_MOTOR)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_UNO) || defined(__AVR_ATmega4809__)
+    #define BOARD AVR
+#elif defined(ARDUINO_AVR_YUN)
+    #define BOARD AVR
 
 // These boards must be installed separately:
-#elif defined(ARDUINO_SAM_DUE)       
-    #define BOARD "Due"
-#elif defined(ARDUINO_SAMD_ZERO)       
-    #define BOARD "Zero"
-#elif defined(ARDUINO_ARC32_TOOLS)       
-    #define BOARD "101"
+#elif defined(ARDUINO_SAM_DUE)
+    #define BOARD SAM
+#elif defined(ARDUINO_SAMD_ZERO)
+    #define BOARD SAMD
+#elif defined(ARDUINO_ARC32_TOOLS)
+    #define BOARD SAM
+#elif defined(ARDUINO_ARDUINO_NANO33BLE)
+    #define BOARD MBED
 #endif
 #endif