diff --git a/include/asm-powerpc/ide.h b/include/asm-powerpc/ide.h
index e61dad7..fd7f5a4 100644
--- a/include/asm-powerpc/ide.h
+++ b/include/asm-powerpc/ide.h
@@ -69,7 +69,7 @@
 
 #ifdef CONFIG_BLK_DEV_MPC8xx_IDE
 #define IDE_ARCH_ACK_INTR  1
-#define ide_ack_intr(hwif) (hwif->hw.ack_intr ? hwif->hw.ack_intr(hwif) : 1)
+#define ide_ack_intr(hwif) ((hwif)->ack_intr ? (hwif)->ack_intr(hwif) : 1)
 #endif
 
 #endif /* __powerpc64__ */