diff --git a/arch/x86_64/kernel/setup64.c b/arch/x86_64/kernel/setup64.c
index 70f1bb808a20e85a98931a2136345228a738e490..349d55c2ac4e35e3413d24f8cef608f87ea56a79 100644
--- a/arch/x86_64/kernel/setup64.c
+++ b/arch/x86_64/kernel/setup64.c
@@ -248,7 +248,7 @@ void __cpuinit cpu_init (void)
 		switch (v + 1) {
 #if DEBUG_STKSZ > EXCEPTION_STKSZ
 		case DEBUG_STACK:
-			cpu_pda[cpu].debugstack = (unsigned long)estacks;
+			cpu_pda(cpu)->debugstack = (unsigned long)estacks;
 			estacks += DEBUG_STKSZ;
 			break;
 #endif