diff --git a/lib/cmsis/CMSIS/Include/core_cmFunc.h b/lib/cmsis/CMSIS/Include/core_cmFunc.h
index 01089f13..d5e32c51 100644
--- a/lib/cmsis/CMSIS/Include/core_cmFunc.h
+++ b/lib/cmsis/CMSIS/Include/core_cmFunc.h
@@ -426,7 +426,7 @@ __attribute__( ( always_inline ) ) __STATIC_INLINE uint32_t __get_PSP(void)
  */
 __attribute__( ( always_inline ) ) __STATIC_INLINE void __set_PSP(uint32_t topOfProcStack)
 {
-  __ASM volatile ("MSR psp, %0\n" : : "r" (topOfProcStack) : "sp");
+  __ASM volatile ("MSR psp, %0\n" : : "r" (topOfProcStack) : );
 }
 
 
@@ -453,7 +453,7 @@ __attribute__( ( always_inline ) ) __STATIC_INLINE uint32_t __get_MSP(void)
  */
 __attribute__( ( always_inline ) ) __STATIC_INLINE void __set_MSP(uint32_t topOfMainStack)
 {
-  __ASM volatile ("MSR msp, %0\n" : : "r" (topOfMainStack) : "sp");
+  __ASM volatile ("MSR msp, %0\n" : : "r" (topOfMainStack) : );
 }
 
 
diff --git a/src/cdc_enumerate.c b/src/cdc_enumerate.c
index b05795fc..3f182550 100644
--- a/src/cdc_enumerate.c
+++ b/src/cdc_enumerate.c
@@ -721,7 +721,7 @@ uint32_t USB_WriteCore(const void *pData, uint32_t length, uint8_t ep_num, bool
 //* \brief Send zero length packet through the control endpoint
 //*----------------------------------------------------------------------------
 void AT91F_USB_SendZlp(void) {
-    uint8_t c;
+    uint8_t c = 0;
     USB_Write(&c, 0, 0);
 }