diff --git a/portable/Common/mpu_wrappers_v2.c b/portable/Common/mpu_wrappers_v2.c
index e257b25c2..3e25757e2 100644
--- a/portable/Common/mpu_wrappers_v2.c
+++ b/portable/Common/mpu_wrappers_v2.c
@@ -263,7 +263,7 @@
                 if( xKernelObjectPool[ i ].xInternalObjectHandle == NULL )
                 {
                     /* Mark this index as not free. */
-                    xKernelObjectPool[ i ].xInternalObjectHandle = ( OpaqueObjectHandle_t ) ( ~0 );
+                    xKernelObjectPool[ i ].xInternalObjectHandle = ( OpaqueObjectHandle_t ) ( ~0U );
                     lFreeIndex = i;
                     break;
                 }