diff --git a/src/common/tusb_fifo.c b/src/common/tusb_fifo.c
index a3933416c..70f514df2 100644
--- a/src/common/tusb_fifo.c
+++ b/src/common/tusb_fifo.c
@@ -82,7 +82,7 @@ bool tu_fifo_config(tu_fifo_t *f, void* buffer, uint16_t depth, uint16_t item_si
   // but limits the maximum depth to 2^16/2 = 2^15 and buffer overflows are detectable
   // only if overflow happens once (important for unsupervised DMA applications)
   //f->max_pointer_idx = (uint16_t) (2*depth - 1);
-  f->non_used_index_space = UINT16_MAX - (2*f->depth-1);
+  f->non_used_index_space = (uint16_t) (UINT16_MAX - (2*f->depth-1));
 
   f->rd_idx = f->wr_idx = 0;
 
@@ -867,7 +867,7 @@ bool tu_fifo_clear(tu_fifo_t *f)
 
   f->rd_idx = f->wr_idx = 0;
   //f->max_pointer_idx = (uint16_t) (2*f->depth-1);
-  f->non_used_index_space = UINT16_MAX - (2*f->depth-1);
+  f->non_used_index_space = (uint16_t) (UINT16_MAX - (2*f->depth-1));
 
   _ff_unlock(f->mutex_wr);
   _ff_unlock(f->mutex_rd);
diff --git a/src/common/tusb_fifo.h b/src/common/tusb_fifo.h
index fd149b75c..932214c81 100644
--- a/src/common/tusb_fifo.h
+++ b/src/common/tusb_fifo.h
@@ -136,13 +136,13 @@ typedef struct
   void * ptr_wrap   ; ///< wrapped part start pointer
 } tu_fifo_buffer_info_t;
 
-#define TU_FIFO_INIT(_buffer, _depth, _type, _overwritable) \
-{                                                           \
-  .buffer               = _buffer,                          \
-  .depth                = _depth,                           \
-  .item_size            = sizeof(_type),                    \
-  .overwritable         = _overwritable,                    \
-  .non_used_index_space = UINT16_MAX - (2*(_depth)-1),      \
+#define TU_FIFO_INIT(_buffer, _depth, _type, _overwritable)        \
+{                                                                  \
+  .buffer               = _buffer,                                 \
+  .depth                = _depth,                                  \
+  .item_size            = sizeof(_type),                           \
+  .overwritable         = _overwritable,                           \
+  .non_used_index_space = (uint16_t)(UINT16_MAX - (2*(_depth)-1)), \
 }
 
 #define TU_FIFO_DEF(_name, _depth, _type, _overwritable)                      \