diff --git a/include/asm-alpha/dma-mapping.h b/include/asm-alpha/dma-mapping.h
index 9dc7256cf979..62d0d6681aa9 100644
--- a/include/asm-alpha/dma-mapping.h
+++ b/include/asm-alpha/dma-mapping.h
@@ -30,6 +30,7 @@
 
 #else	/* no PCI - no IOMMU. */
 
+struct scatterlist;
 void *dma_alloc_coherent(struct device *dev, size_t size,
 			 dma_addr_t *dma_handle, gfp_t gfp);
 int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,