diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index 786539e..a6d0586 100644
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -1,3 +1,6 @@
+#ifndef _LINUX_IOMMU_HELPER_H
+#define _LINUX_IOMMU_HELPER_H
+
 static inline unsigned long iommu_device_max_index(unsigned long size,
 						   unsigned long offset,
 						   u64 dma_mask)
@@ -19,3 +22,5 @@
 				      unsigned long align_mask);
 extern void iommu_area_free(unsigned long *map, unsigned long start,
 			    unsigned int nr);
+
+#endif