diff --git a/crypto/fipsmodule/bn/asm/x86_64-mont5.pl b/crypto/fipsmodule/bn/asm/x86_64-mont5.pl
index 806e6f5..442e696 100755
--- a/crypto/fipsmodule/bn/asm/x86_64-mont5.pl
+++ b/crypto/fipsmodule/bn/asm/x86_64-mont5.pl
@@ -2898,6 +2898,7 @@
 .align	32
 bn_sqrx8x_internal:
 __bn_sqrx8x_internal:
+.cfi_startproc
 	##################################################################
 	# Squaring part:
 	#
@@ -3530,6 +3531,7 @@
 	cmp	8+8(%rsp),%r8		# end of t[]?
 	jb	.Lsqrx8x_reduction_loop
 	ret
+.cfi_endproc
 .size	bn_sqrx8x_internal,.-bn_sqrx8x_internal
 ___
 }
diff --git a/crypto/fipsmodule/bn/bn_test.cc b/crypto/fipsmodule/bn/bn_test.cc
index 258d01b..be0a86e 100644
--- a/crypto/fipsmodule/bn/bn_test.cc
+++ b/crypto/fipsmodule/bn/bn_test.cc
@@ -87,6 +87,7 @@
 
 #include "./internal.h"
 #include "../../internal.h"
+#include "../../test/abi_test.h"
 #include "../../test/file_test.h"
 #include "../../test/test_util.h"
 
@@ -2377,3 +2378,28 @@
   EXPECT_TRUE(BN_is_word(r.get(), 6));
   EXPECT_FALSE(BN_is_negative(r.get()));
 }
+
+#if defined(OPENSSL_BN_ASM_MONT) && defined(SUPPORTS_ABI_TEST)
+TEST_F(BNTest, BNMulMontABI) {
+  for (size_t words : {4, 5, 6, 7, 8, 16, 32}) {
+    SCOPED_TRACE(words);
+
+    bssl::UniquePtr<BIGNUM> m(BN_new());
+    ASSERT_TRUE(m);
+    ASSERT_TRUE(BN_set_bit(m.get(), 0));
+    ASSERT_TRUE(BN_set_bit(m.get(), words * BN_BITS2 - 1));
+    bssl::UniquePtr<BN_MONT_CTX> mont(
+        BN_MONT_CTX_new_for_modulus(m.get(), ctx()));
+    ASSERT_TRUE(mont);
+
+    std::vector<BN_ULONG> r(words), a(words), b(words);
+    a[0] = 1;
+    b[0] = 42;
+
+    CHECK_ABI(bn_mul_mont, r.data(), a.data(), b.data(), mont->N.d, mont->n0,
+              words);
+    CHECK_ABI(bn_mul_mont, r.data(), a.data(), a.data(), mont->N.d, mont->n0,
+              words);
+  }
+}
+#endif   // OPENSSL_BN_ASM_MONT && SUPPORTS_ABI_TEST
diff --git a/crypto/fipsmodule/bn/internal.h b/crypto/fipsmodule/bn/internal.h
index fb8d11f..0bcc031 100644
--- a/crypto/fipsmodule/bn/internal.h
+++ b/crypto/fipsmodule/bn/internal.h
@@ -336,8 +336,13 @@
 int bn_rand_secret_range(BIGNUM *r, int *out_is_uniform, BN_ULONG min_inclusive,
                          const BIGNUM *max_exclusive);
 
+#if !defined(OPENSSL_NO_ASM) &&                         \
+    (defined(OPENSSL_X86) || defined(OPENSSL_X86_64) || \
+     defined(OPENSSL_ARM) || defined(OPENSSL_AARCH64))
+#define OPENSSL_BN_ASM_MONT
 int bn_mul_mont(BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp,
                 const BN_ULONG *np, const BN_ULONG *n0, int num);
+#endif
 
 uint64_t bn_mont_n0(const BIGNUM *n);
 
diff --git a/crypto/fipsmodule/bn/montgomery.c b/crypto/fipsmodule/bn/montgomery.c
index 006d2b2..b6eaf6a 100644
--- a/crypto/fipsmodule/bn/montgomery.c
+++ b/crypto/fipsmodule/bn/montgomery.c
@@ -122,13 +122,6 @@
 #include "../../internal.h"
 
 
-#if !defined(OPENSSL_NO_ASM) &&                         \
-    (defined(OPENSSL_X86) || defined(OPENSSL_X86_64) || \
-     defined(OPENSSL_ARM) || defined(OPENSSL_AARCH64))
-#define OPENSSL_BN_ASM_MONT
-#endif
-
-
 BN_MONT_CTX *BN_MONT_CTX_new(void) {
   BN_MONT_CTX *ret = OPENSSL_malloc(sizeof(BN_MONT_CTX));