diff --git a/arch/parisc/include/asm/agp.h b/arch/parisc/include/asm/agp.h
index cb04470e63d0c7c3c8e43c81fd09267a9f2c1c87..14ae54cfd36880ae5fe496804996d68cf3a83382 100644
--- a/arch/parisc/include/asm/agp.h
+++ b/arch/parisc/include/asm/agp.h
@@ -8,8 +8,8 @@
  *
  */
 
-#define map_page_into_agp(page)		/* nothing */
-#define unmap_page_from_agp(page)	/* nothing */
+#define map_page_into_agp(page)		do { } while (0)
+#define unmap_page_from_agp(page)	do { } while (0)
 #define flush_agp_cache()		mb()
 
 /* GATT allocation. Returns/accepts GATT kernel virtual address. */
diff --git a/arch/powerpc/include/asm/agp.h b/arch/powerpc/include/asm/agp.h
index b29b1186f8193873a5fe2b23019e46e147ba1cf2..6b6485c988dd8fd85a3063a9f26dd38592ac3bc0 100644
--- a/arch/powerpc/include/asm/agp.h
+++ b/arch/powerpc/include/asm/agp.h
@@ -5,8 +5,8 @@
 
 #include <asm/io.h>
 
-#define map_page_into_agp(page)
-#define unmap_page_from_agp(page)
+#define map_page_into_agp(page) do {} while (0)
+#define unmap_page_from_agp(page) do {} while (0)
 #define flush_agp_cache() mb()
 
 /* GATT allocation. Returns/accepts GATT kernel virtual address. */
diff --git a/arch/sparc/include/asm/agp.h b/arch/sparc/include/asm/agp.h
index efe0d6a12e5a8bff8cf139f12fffff1e07a9921d..2d0ff84cee3fd1ac93545cba2641e8d8b4fc97d3 100644
--- a/arch/sparc/include/asm/agp.h
+++ b/arch/sparc/include/asm/agp.h
@@ -4,9 +4,9 @@
 
 /* dummy for now */
 
-#define map_page_into_agp(page)
-#define unmap_page_from_agp(page)
-#define flush_agp_cache() mb()
+#define map_page_into_agp(page)		do { } while (0)
+#define unmap_page_from_agp(page)	do { } while (0)
+#define flush_agp_cache()		mb()
 
 /* GATT allocation. Returns/accepts GATT kernel virtual address. */
 #define alloc_gatt_pages(order)		\