diff --git a/crypto/fipsmodule/bn/bn_tests.txt b/crypto/fipsmodule/bn/bn_tests.txt
index 4bc1fa2..9a1a5db 100644
--- a/crypto/fipsmodule/bn/bn_tests.txt
+++ b/crypto/fipsmodule/bn/bn_tests.txt
@@ -10625,12 +10625,10 @@
 M = 8f42c9e9e351ba9b32ab0cf69da43f4acf7028d19cff6e5059ea0e3fcc97c97f36a31470044737d4c0c933ac441ecb29e32c81401523afdac7de9c3fd8493c97
 
 # 1024-bit
-# TODO(davidben): This test breaks the RSAZ implementation. Fix it and enable
-# this test.
-# ModExp = 00
-# A = 800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002f
-# E = ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
-# M = 9da8dc26fdf4d2e49833b240ee552beb7a6e251caa91bfb5d6cafaf8ed9461877fda8f6ac299036d35806bc1ae7872e54eaac1ec6bee6d02c6621a9cf8883b3abc33c49b3e601203e0e86ef8f0562412cc689ee2670704583909ca6d7774c9f9f9f4d77d37fedef9cb51d207cb629ec02fa03b526fd6594bfa8f2da71238a0b7
+ModExp = 00
+A = 800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002f
+E = ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
+M = 9da8dc26fdf4d2e49833b240ee552beb7a6e251caa91bfb5d6cafaf8ed9461877fda8f6ac299036d35806bc1ae7872e54eaac1ec6bee6d02c6621a9cf8883b3abc33c49b3e601203e0e86ef8f0562412cc689ee2670704583909ca6d7774c9f9f9f4d77d37fedef9cb51d207cb629ec02fa03b526fd6594bfa8f2da71238a0b7
 
 # 1025-bit
 ModExp = 00
diff --git a/crypto/fipsmodule/bn/rsaz_exp.c b/crypto/fipsmodule/bn/rsaz_exp.c
index 7e15aaf..074f05d 100644
--- a/crypto/fipsmodule/bn/rsaz_exp.c
+++ b/crypto/fipsmodule/bn/rsaz_exp.c
@@ -219,6 +219,8 @@
   rsaz_1024_mul_avx2(result, result, one, m, k0);
 
   rsaz_1024_red2norm_avx2(result_norm, result);
+  BN_ULONG scratch[16];
+  bn_reduce_once_in_place(result_norm, /*carry=*/0, m_norm, scratch, 16);
 
   OPENSSL_cleanse(storage, MOD_EXP_CTIME_STORAGE_LEN * sizeof(BN_ULONG));
 }
diff --git a/crypto/fipsmodule/bn/rsaz_exp.h b/crypto/fipsmodule/bn/rsaz_exp.h
index 104bb7a..bc7a439 100644
--- a/crypto/fipsmodule/bn/rsaz_exp.h
+++ b/crypto/fipsmodule/bn/rsaz_exp.h
@@ -90,7 +90,11 @@
                             int i);
 
 // rsaz_1024_red2norm_avx2 converts |red| from RSAZ to |BIGNUM| representation
-// and writes the result to |norm|.
+// and writes the result to |norm|. The result will be <= the modulus.
+//
+// WARNING: The result of this operation may not be fully reduced. |norm| may be
+// the modulus instead of zero. This function should be followed by a call to
+// |bn_reduce_once|.
 void rsaz_1024_red2norm_avx2(BN_ULONG norm[16], const BN_ULONG red[40]);