diff --git a/tools/arch/x86/kcpuid/kcpuid.c b/tools/arch/x86/kcpuid/kcpuid.c
index 7790136f04dc..1f48de343d4d 100644
--- a/tools/arch/x86/kcpuid/kcpuid.c
+++ b/tools/arch/x86/kcpuid/kcpuid.c
@@ -71,7 +71,7 @@ enum range_index {
 	RANGE_EXT = 0x80000000,		/* Extended */
 };
 
-#define CPUID_INDEX_MASK		0x80000000
+#define CPUID_INDEX_MASK		0xffff0000
 #define CPUID_FUNCTION_MASK		(~CPUID_INDEX_MASK)
 
 struct cpuid_range {
@@ -173,7 +173,7 @@ static bool cpuid_store(struct cpuid_range *range, u32 f, int subleaf,
 	 * Cut off vendor-prefix from CPUID function as we're using it as an
 	 * index into ->funcs.
 	 */
-	func = &range->funcs[f & 0xffff];
+	func = &range->funcs[f & CPUID_FUNCTION_MASK];
 
 	if (!func->leafs) {
 		func->leafs = malloc(sizeof(struct subleaf));
@@ -228,7 +228,7 @@ void setup_cpuid_range(struct cpuid_range *range)
 
 	cpuid(range->index, max_func, ebx, ecx, edx);
 
-	idx_func = (max_func & 0xffff) + 1;
+	idx_func = (max_func & CPUID_FUNCTION_MASK) + 1;
 	range->funcs = malloc(sizeof(struct cpuid_func) * idx_func);
 	if (!range->funcs)
 		err(EXIT_FAILURE, NULL);
@@ -512,7 +512,7 @@ static inline struct cpuid_func *index_to_func(u32 index)
 	if (!range)
 		return NULL;
 
-	func_idx = index & 0xffff;
+	func_idx = index & CPUID_FUNCTION_MASK;
 	if ((func_idx + 1) > (u32)range->nr)
 		return NULL;