diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 58acda5038178e7c8bad16333444a40f2d84765c..59bf91c57aa85d36a78d4db5b98e3f9921bbe155 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -61,6 +61,13 @@ extern const char * const x86_bug_flags[NBUGINTS*32];
 #define CHECK_BIT_IN_MASK_WORD(maskname, word, bit)	\
 	(((bit)>>5)==(word) && (1UL<<((bit)&31) & maskname##word ))
 
+/*
+ * {REQUIRED,DISABLED}_MASK_CHECK below may seem duplicated with the
+ * following BUILD_BUG_ON_ZERO() check but when NCAPINTS gets changed, all
+ * header macros which use NCAPINTS need to be changed. The duplicated macro
+ * use causes the compiler to issue errors for all headers so that all usage
+ * sites can be corrected.
+ */
 #define REQUIRED_MASK_BIT_SET(feature_bit)		\
 	 ( CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  0, feature_bit) ||	\
 	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  1, feature_bit) ||	\