diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index b0cc3809723d4f50bb7009691eabdfa9682b81e1..6e2537c3219060b31a9344c5df0dd90d8d3afbd2 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -240,7 +240,7 @@ static u32 __init intel_stolen_base(int num, int slot, int func, size_t stolen_s
 	return base;
 }
 
-#define KB(x)	((x) * 1024)
+#define KB(x)	((x) * 1024UL)
 #define MB(x)	(KB (KB (x)))
 #define GB(x)	(MB (KB (x)))