diff --git a/winsup/cygwin/scripts/gendef b/winsup/cygwin/scripts/gendef
index 6328fe2fbd..8a162925e3 100755
--- a/winsup/cygwin/scripts/gendef
+++ b/winsup/cygwin/scripts/gendef
@@ -232,6 +232,7 @@ sigdelayed:
 	movl	\$0x0d,%eax
 	xorl	%ecx,%ecx
 	cpuid	# get necessary space for xsave
+	movl	%ebx,%ebx # clear upper 32 bits from a faulty CPUID implementation
 	movq	%rbx,%rcx
 	addq	\$63, %rbx
 	andq	\$-64, %rbx # align to next 64-byte multiple