diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 4abda074ea45..3c365ab6cf5f 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -537,8 +537,9 @@ EXPORT_SYMBOL_GPL(swiotlb_tbl_map_single);
  * Allocates bounce buffer and returns its kernel virtual address.
  */
 
-phys_addr_t map_single(struct device *hwdev, phys_addr_t phys, size_t size,
-		       enum dma_data_direction dir)
+static phys_addr_t
+map_single(struct device *hwdev, phys_addr_t phys, size_t size,
+	   enum dma_data_direction dir)
 {
 	dma_addr_t start_dma_addr = phys_to_dma(hwdev, io_tlb_start);