diff --git a/libraries/AP_HAL_SMACCM/Console.cpp b/libraries/AP_HAL_SMACCM/Console.cpp
index dfb0f853e8..7528a67084 100644
--- a/libraries/AP_HAL_SMACCM/Console.cpp
+++ b/libraries/AP_HAL_SMACCM/Console.cpp
@@ -155,10 +155,10 @@ bool SMACCMConsoleDriver::Buffer::allocate(uint16_t size)
   uint8_t shift;
   /* Hardcoded max size of 1024. sue me. */
   for ( shift = 1;
-        ( 1 << shift ) < 1024 && ( 1 << shift) < size;
+        ( 1U << shift ) < 1024 && ( 1U << shift) < size;
         shift++
     ) ;
-  uint16_t tmpmask  = (1 << shift) - 1;
+  uint16_t tmpmask  = (1U << shift) - 1;
 
   if ( _bytes != NULL ) {
     if ( _mask == tmpmask ) {