diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 474bbc875..8bffa819e 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,8 @@
+2015-11-28  Corinna Vinschen  <corinna@vinschen.de>
+
+	* gendef (sigdelayed): Save and restore content of the MXCSR register
+	on x86_64.
+
 2015-11-27  Corinna Vinschen  <corinna@vinschen.de>
 
 	* cygtls.h (_cygtls::wait_signal_arrived): Renamed from
diff --git a/winsup/cygwin/gendef b/winsup/cygwin/gendef
index 986827773..9d6f1b40b 100755
--- a/winsup/cygwin/gendef
+++ b/winsup/cygwin/gendef
@@ -229,6 +229,7 @@ sigdelayed:
 	.seh_pushreg %rax
 	subq	\$0x128,%rsp
 	.seh_stackalloc 0x128
+	stmxcsr	0x124(%rsp)
 	fnstcw	0x120(%rsp)
 	movdqa	%xmm15,0x110(%rsp)
 	movdqa	%xmm14,0x100(%rsp)
@@ -290,6 +291,7 @@ sigdelayed:
 	movdqa	0x110(%rsp),%xmm15
 	fninit
 	fldcw	0x120(%rsp)
+	ldmxcsr	0x124(%rsp)
 	addq	\$0x128,%rsp
 	popq	%rax
 	popq	%rbx