diff --git a/targets/TARGET_NXP/TARGET_LPC11UXX/device/cmsis_nvic.c b/targets/TARGET_NXP/TARGET_LPC11UXX/device/cmsis_nvic.c
index 4127988d620..5f6802e6d27 100644
--- a/targets/TARGET_NXP/TARGET_LPC11UXX/device/cmsis_nvic.c
+++ b/targets/TARGET_NXP/TARGET_LPC11UXX/device/cmsis_nvic.c
@@ -60,7 +60,8 @@ void NVIC_SetVector(IRQn_Type IRQn, uint32_t vector) {
     
     // Copy and switch to dynamic vectors if first time called
     if((LPC_SYSCON->SYSMEMREMAP & 0x3) != 0x1) {     
-      uint32_t *old_vectors = (uint32_t *)0;         // FLASH vectors are at 0x0
+      // Add volatile qualifier to avoid armclang aggressive optimization
+      volatile uint32_t *old_vectors = (uint32_t *)0;         // FLASH vectors are at 0x0
       for(i = 0; i < NVIC_NUM_VECTORS; i++) {    
             vectors[i] = old_vectors[i];
         }
diff --git a/targets/TARGET_NXP/TARGET_LPC11UXX/us_ticker.c b/targets/TARGET_NXP/TARGET_LPC11UXX/us_ticker.c
index 5299b4a7bbc..0ae71396742 100644
--- a/targets/TARGET_NXP/TARGET_LPC11UXX/us_ticker.c
+++ b/targets/TARGET_NXP/TARGET_LPC11UXX/us_ticker.c
@@ -17,6 +17,8 @@
 #include "us_ticker_api.h"
 #include "PeripheralNames.h"
 
+#if DEVICE_USTICKER
+
 #define US_TICKER_TIMER          ((LPC_CTxxBx_Type *)LPC_CT32B1_BASE)
 #define US_TICKER_TIMER_IRQn     TIMER_32_1_IRQn
 
@@ -70,3 +72,5 @@ void us_ticker_free(void)
 {
 
 }
+
+#endif // DEVICE_USTICKER
diff --git a/targets/targets.json b/targets/targets.json
index 1040f6fd55a..efafdcbd54f 100644
--- a/targets/targets.json
+++ b/targets/targets.json
@@ -374,8 +374,13 @@
             "SERIAL",
             "SLEEP",
             "SPI",
-            "SPISLAVE"
+            "SPISLAVE",
+            "USTICKER"
         ],
+        "overrides": {
+            "tickless-from-us-ticker"   : true,
+            "boot-stack-size"           : "0x400"
+        },
         "default_lib": "small",
         "release_versions": ["2"],
         "device_name": "LPC11U35FBD48/401"