diff --git a/crypto/fipsmodule/bn/asm/x86_64-mont5.pl b/crypto/fipsmodule/bn/asm/x86_64-mont5.pl
index dfb8b37..69b8e01 100755
--- a/crypto/fipsmodule/bn/asm/x86_64-mont5.pl
+++ b/crypto/fipsmodule/bn/asm/x86_64-mont5.pl
@@ -3190,11 +3190,19 @@
 
 .align	32
 .Lsqrx8x_break:
-	sub	16+8(%rsp),%r8		# consume last carry
+	xor	$zero,$zero
+	sub	16+8(%rsp),%rbx		# mov 16(%rsp),%cf
+	adcx	$zero,%r8
 	mov	24+8(%rsp),$carry	# initial $tptr, borrow $carry
+	adcx	$zero,%r9
 	mov	0*8($aptr),%rdx		# a[8], modulo-scheduled
-	xor	%ebp,%ebp		# xor	$zero,$zero
+	adc	\$0,%r10
 	mov	%r8,0*8($tptr)
+	adc	\$0,%r11
+	adc	\$0,%r12
+	adc	\$0,%r13
+	adc	\$0,%r14
+	adc	\$0,%r15
 	cmp	$carry,$tptr		# cf=0, of=0
 	je	.Lsqrx8x_outer_loop
 
diff --git a/crypto/fipsmodule/bn/bn_tests.txt b/crypto/fipsmodule/bn/bn_tests.txt
index c53eb23..f809e7e 100644
--- a/crypto/fipsmodule/bn/bn_tests.txt
+++ b/crypto/fipsmodule/bn/bn_tests.txt
@@ -9897,6 +9897,12 @@
 A = ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00000000000000ffffffff00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000ffffffffffffff00000000
 M = ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00000000000000ffffffff00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000ffffffffffffff
 
+# Regression test for CVE-2017-3736.
+ModSquare = fe06fe0b06160c09
+A = fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff8f8f8f800000000000010000000006c000000000000000000000000000000000000000000000000000000000000000000000000000000000000fffffffffffff8f8f8f800000000000010000000006c000000000000000000000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000000000000000000000000000000000ffffffffffffffffffffffffffffffffffff00000000ffffffffffffffffffffffffffff00fcfdfc
+# A in Montgomery form is 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
+M = fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff8f8f8f800000000000010000000006c000000000000000000000000000000000000000000000000000000000000000000000000000000000000fffffffffffff8f8f8f800000000000010000000006c000000000000000000000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000000000000000000000000000000000ffffffffffffffffffffffffffffffffffff00000000ffffffffffffffffffffffffffffffffffff
+
 
 # ModExp tests.
 #