diff --git a/acme/version_go112.go b/acme/version_go112.go
index b58f245..b9efdb5 100644
--- a/acme/version_go112.go
+++ b/acme/version_go112.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.12
 // +build go1.12
 
 package acme
diff --git a/argon2/blamka_amd64.go b/argon2/blamka_amd64.go
index 1108e11..a014ac9 100644
--- a/argon2/blamka_amd64.go
+++ b/argon2/blamka_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build amd64 && gc && !purego
 // +build amd64,gc,!purego
 
 package argon2
diff --git a/argon2/blamka_ref.go b/argon2/blamka_ref.go
index 4a963c7..167c59d 100644
--- a/argon2/blamka_ref.go
+++ b/argon2/blamka_ref.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !amd64 || purego || !gc
 // +build !amd64 purego !gc
 
 package argon2
diff --git a/blake2b/blake2bAVX2_amd64.go b/blake2b/blake2bAVX2_amd64.go
index 8a893fd..56bfaaa 100644
--- a/blake2b/blake2bAVX2_amd64.go
+++ b/blake2b/blake2bAVX2_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.7 && amd64 && gc && !purego
 // +build go1.7,amd64,gc,!purego
 
 package blake2b
diff --git a/blake2b/blake2b_amd64.go b/blake2b/blake2b_amd64.go
index a52c887..5fa1b32 100644
--- a/blake2b/blake2b_amd64.go
+++ b/blake2b/blake2b_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !go1.7 && amd64 && gc && !purego
 // +build !go1.7,amd64,gc,!purego
 
 package blake2b
diff --git a/blake2b/blake2b_ref.go b/blake2b/blake2b_ref.go
index 8597457..b0137cd 100644
--- a/blake2b/blake2b_ref.go
+++ b/blake2b/blake2b_ref.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !amd64 || purego || !gc
 // +build !amd64 purego !gc
 
 package blake2b
diff --git a/blake2b/register.go b/blake2b/register.go
index efd689a..9d86339 100644
--- a/blake2b/register.go
+++ b/blake2b/register.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.9
 // +build go1.9
 
 package blake2b
diff --git a/blake2s/blake2s_386.go b/blake2s/blake2s_386.go
index 2d8ee63..b4463fb 100644
--- a/blake2s/blake2s_386.go
+++ b/blake2s/blake2s_386.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build 386 && gc && !purego
 // +build 386,gc,!purego
 
 package blake2s
diff --git a/blake2s/blake2s_amd64.go b/blake2s/blake2s_amd64.go
index 267bdce..becdaa1 100644
--- a/blake2s/blake2s_amd64.go
+++ b/blake2s/blake2s_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build amd64 && gc && !purego
 // +build amd64,gc,!purego
 
 package blake2s
diff --git a/blake2s/blake2s_ref.go b/blake2s/blake2s_ref.go
index 94ef01d..799dba0 100644
--- a/blake2s/blake2s_ref.go
+++ b/blake2s/blake2s_ref.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build (!amd64 && !386) || !gc || purego
 // +build !amd64,!386 !gc purego
 
 package blake2s
diff --git a/blake2s/register.go b/blake2s/register.go
index d277459..ef79ff3 100644
--- a/blake2s/register.go
+++ b/blake2s/register.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.9
 // +build go1.9
 
 package blake2s
diff --git a/chacha20/chacha_arm64.go b/chacha20/chacha_arm64.go
index c474e5a..94c71ac 100644
--- a/chacha20/chacha_arm64.go
+++ b/chacha20/chacha_arm64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.11 && gc && !purego
 // +build go1.11,gc,!purego
 
 package chacha20
diff --git a/chacha20/chacha_noasm.go b/chacha20/chacha_noasm.go
index 3e8a609..025b498 100644
--- a/chacha20/chacha_noasm.go
+++ b/chacha20/chacha_noasm.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build (!arm64 && !s390x && !ppc64le) || (arm64 && !go1.11) || !gc || purego
 // +build !arm64,!s390x,!ppc64le arm64,!go1.11 !gc purego
 
 package chacha20
diff --git a/chacha20/chacha_ppc64le.go b/chacha20/chacha_ppc64le.go
index 2806c63..da420b2 100644
--- a/chacha20/chacha_ppc64le.go
+++ b/chacha20/chacha_ppc64le.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gc && !purego
 // +build gc,!purego
 
 package chacha20
diff --git a/chacha20/chacha_s390x.go b/chacha20/chacha_s390x.go
index a0774dd..c5898db 100644
--- a/chacha20/chacha_s390x.go
+++ b/chacha20/chacha_s390x.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gc && !purego
 // +build gc,!purego
 
 package chacha20
diff --git a/chacha20poly1305/chacha20poly1305_amd64.go b/chacha20poly1305/chacha20poly1305_amd64.go
index c41d061..25959b9 100644
--- a/chacha20poly1305/chacha20poly1305_amd64.go
+++ b/chacha20poly1305/chacha20poly1305_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gc && !purego
 // +build gc,!purego
 
 package chacha20poly1305
diff --git a/chacha20poly1305/chacha20poly1305_noasm.go b/chacha20poly1305/chacha20poly1305_noasm.go
index 13941c4..f832b33 100644
--- a/chacha20poly1305/chacha20poly1305_noasm.go
+++ b/chacha20poly1305/chacha20poly1305_noasm.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !amd64 || !gc || purego
 // +build !amd64 !gc purego
 
 package chacha20poly1305
diff --git a/curve25519/curve25519_amd64.go b/curve25519/curve25519_amd64.go
index 877b6de..8485848 100644
--- a/curve25519/curve25519_amd64.go
+++ b/curve25519/curve25519_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build amd64 && gc && !purego
 // +build amd64,gc,!purego
 
 package curve25519
diff --git a/curve25519/curve25519_noasm.go b/curve25519/curve25519_noasm.go
index 80d3300..259728a 100644
--- a/curve25519/curve25519_noasm.go
+++ b/curve25519/curve25519_noasm.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !amd64 || !gc || purego
 // +build !amd64 !gc purego
 
 package curve25519
diff --git a/ed25519/ed25519.go b/ed25519/ed25519.go
index c7f8c7e..71ad917 100644
--- a/ed25519/ed25519.go
+++ b/ed25519/ed25519.go
@@ -5,6 +5,7 @@
 // In Go 1.13, the ed25519 package was promoted to the standard library as
 // crypto/ed25519, and this package became a wrapper for the standard library one.
 //
+//go:build !go1.13
 // +build !go1.13
 
 // Package ed25519 implements the Ed25519 signature algorithm. See
diff --git a/ed25519/ed25519_go113.go b/ed25519/ed25519_go113.go
index d1448d8..b5974dc 100644
--- a/ed25519/ed25519_go113.go
+++ b/ed25519/ed25519_go113.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.13
 // +build go1.13
 
 // Package ed25519 implements the Ed25519 signature algorithm. See
diff --git a/ed25519/go113_test.go b/ed25519/go113_test.go
index 76edde0..7a3912f 100644
--- a/ed25519/go113_test.go
+++ b/ed25519/go113_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.13
 // +build go1.13
 
 package ed25519_test
diff --git a/internal/subtle/aliasing.go b/internal/subtle/aliasing.go
index 281c27e..4fad24f 100644
--- a/internal/subtle/aliasing.go
+++ b/internal/subtle/aliasing.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !purego
 // +build !purego
 
 // Package subtle implements functions that are often useful in cryptographic
diff --git a/internal/subtle/aliasing_purego.go b/internal/subtle/aliasing_purego.go
index e20a296..80ccbed 100644
--- a/internal/subtle/aliasing_purego.go
+++ b/internal/subtle/aliasing_purego.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build purego
 // +build purego
 
 // Package subtle implements functions that are often useful in cryptographic
diff --git a/internal/wycheproof/ecdsa_compat_test.go b/internal/wycheproof/ecdsa_compat_test.go
index 8edc10b..5880fb3 100644
--- a/internal/wycheproof/ecdsa_compat_test.go
+++ b/internal/wycheproof/ecdsa_compat_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !go1.15
 // +build !go1.15
 
 // ecdsa.VerifyASN1 was added in Go 1.15.
diff --git a/internal/wycheproof/ecdsa_go115_test.go b/internal/wycheproof/ecdsa_go115_test.go
index 8da3be5..e13e709 100644
--- a/internal/wycheproof/ecdsa_go115_test.go
+++ b/internal/wycheproof/ecdsa_go115_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.15
 // +build go1.15
 
 package wycheproof
diff --git a/internal/wycheproof/eddsa_test.go b/internal/wycheproof/eddsa_test.go
index 06c9829..0a7fbb7 100644
--- a/internal/wycheproof/eddsa_test.go
+++ b/internal/wycheproof/eddsa_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.13
 // +build go1.13
 
 package wycheproof
diff --git a/ocsp/ocsp_test.go b/ocsp/ocsp_test.go
index 70b1976..a6f7c48 100644
--- a/ocsp/ocsp_test.go
+++ b/ocsp/ocsp_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.7
 // +build go1.7
 
 package ocsp
diff --git a/poly1305/bits_compat.go b/poly1305/bits_compat.go
index 157a69f..45b5c96 100644
--- a/poly1305/bits_compat.go
+++ b/poly1305/bits_compat.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !go1.13
 // +build !go1.13
 
 package poly1305
diff --git a/poly1305/bits_go1.13.go b/poly1305/bits_go1.13.go
index a0a185f..ed52b34 100644
--- a/poly1305/bits_go1.13.go
+++ b/poly1305/bits_go1.13.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.13
 // +build go1.13
 
 package poly1305
diff --git a/poly1305/mac_noasm.go b/poly1305/mac_noasm.go
index af6c94f..f184b67 100644
--- a/poly1305/mac_noasm.go
+++ b/poly1305/mac_noasm.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build (!amd64 && !ppc64le && !s390x) || !gc || purego
 // +build !amd64,!ppc64le,!s390x !gc purego
 
 package poly1305
diff --git a/poly1305/sum_amd64.go b/poly1305/sum_amd64.go
index cf3a69e..6d52233 100644
--- a/poly1305/sum_amd64.go
+++ b/poly1305/sum_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gc && !purego
 // +build gc,!purego
 
 package poly1305
diff --git a/poly1305/sum_ppc64le.go b/poly1305/sum_ppc64le.go
index cb4b718..4a06994 100644
--- a/poly1305/sum_ppc64le.go
+++ b/poly1305/sum_ppc64le.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gc && !purego
 // +build gc,!purego
 
 package poly1305
diff --git a/poly1305/sum_s390x.go b/poly1305/sum_s390x.go
index 188a665..62cc9f8 100644
--- a/poly1305/sum_s390x.go
+++ b/poly1305/sum_s390x.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gc && !purego
 // +build gc,!purego
 
 package poly1305
diff --git a/salsa20/salsa/salsa20_amd64.go b/salsa20/salsa/salsa20_amd64.go
index 5cf1d6d..c400dfc 100644
--- a/salsa20/salsa/salsa20_amd64.go
+++ b/salsa20/salsa/salsa20_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build amd64 && !purego && gc
 // +build amd64,!purego,gc
 
 package salsa
diff --git a/salsa20/salsa/salsa20_amd64_test.go b/salsa20/salsa/salsa20_amd64_test.go
index a9cb697..fc781f7 100644
--- a/salsa20/salsa/salsa20_amd64_test.go
+++ b/salsa20/salsa/salsa20_amd64_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build amd64 && !purego && gc
 // +build amd64,!purego,gc
 
 package salsa
diff --git a/salsa20/salsa/salsa20_noasm.go b/salsa20/salsa/salsa20_noasm.go
index 24f03c1..4392cc1 100644
--- a/salsa20/salsa/salsa20_noasm.go
+++ b/salsa20/salsa/salsa20_noasm.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !amd64 || purego || !gc
 // +build !amd64 purego !gc
 
 package salsa
diff --git a/sha3/hashes_generic.go b/sha3/hashes_generic.go
index fac0c0e..c74fc20 100644
--- a/sha3/hashes_generic.go
+++ b/sha3/hashes_generic.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !gc || purego || !s390x
 // +build !gc purego !s390x
 
 package sha3
diff --git a/sha3/keccakf.go b/sha3/keccakf.go
index 92b63a3..0f4ae8b 100644
--- a/sha3/keccakf.go
+++ b/sha3/keccakf.go
@@ -2,7 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//  +build !amd64 purego !gc
+//go:build !amd64 || purego || !gc
+// +build !amd64 purego !gc
 
 package sha3
 
diff --git a/sha3/keccakf_amd64.go b/sha3/keccakf_amd64.go
index 3e3e760..248a382 100644
--- a/sha3/keccakf_amd64.go
+++ b/sha3/keccakf_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build amd64 && !purego && gc
 // +build amd64,!purego,gc
 
 package sha3
diff --git a/sha3/register.go b/sha3/register.go
index 3cf6a22..8b4453a 100644
--- a/sha3/register.go
+++ b/sha3/register.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.4
 // +build go1.4
 
 package sha3
diff --git a/sha3/sha3_s390x.go b/sha3/sha3_s390x.go
index 485e2d5..4fcfc92 100644
--- a/sha3/sha3_s390x.go
+++ b/sha3/sha3_s390x.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gc && !purego
 // +build gc,!purego
 
 package sha3
diff --git a/sha3/shake_generic.go b/sha3/shake_generic.go
index 68148f2..5c0710e 100644
--- a/sha3/shake_generic.go
+++ b/sha3/shake_generic.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !gc || purego || !s390x
 // +build !gc purego !s390x
 
 package sha3
diff --git a/sha3/xor.go b/sha3/xor.go
index ddafa82..59c8eb9 100644
--- a/sha3/xor.go
+++ b/sha3/xor.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build (!amd64 && !386 && !ppc64le) || purego
 // +build !amd64,!386,!ppc64le purego
 
 package sha3
diff --git a/sha3/xor_unaligned.go b/sha3/xor_unaligned.go
index 6249ad8..1ce6062 100644
--- a/sha3/xor_unaligned.go
+++ b/sha3/xor_unaligned.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build (amd64 || 386 || ppc64le) && !purego
 // +build amd64 386 ppc64le
 // +build !purego
 
diff --git a/ssh/test/agent_unix_test.go b/ssh/test/agent_unix_test.go
index 5d320d0..9df2b4e 100644
--- a/ssh/test/agent_unix_test.go
+++ b/ssh/test/agent_unix_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd
 // +build aix darwin dragonfly freebsd linux netbsd openbsd
 
 package test
diff --git a/ssh/test/banner_test.go b/ssh/test/banner_test.go
index c3f0a08..f149d6d 100644
--- a/ssh/test/banner_test.go
+++ b/ssh/test/banner_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd
 // +build aix darwin dragonfly freebsd linux netbsd openbsd
 
 package test
diff --git a/ssh/test/cert_test.go b/ssh/test/cert_test.go
index 84ac31e..8506e4b 100644
--- a/ssh/test/cert_test.go
+++ b/ssh/test/cert_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd
 // +build aix darwin dragonfly freebsd linux netbsd openbsd
 
 package test
diff --git a/ssh/test/dial_unix_test.go b/ssh/test/dial_unix_test.go
index 8e1362c..15c34d9 100644
--- a/ssh/test/dial_unix_test.go
+++ b/ssh/test/dial_unix_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows && !solaris && !js
 // +build !windows,!solaris,!js
 
 package test
diff --git a/ssh/test/forward_unix_test.go b/ssh/test/forward_unix_test.go
index 4c44e57..ab8e639 100644
--- a/ssh/test/forward_unix_test.go
+++ b/ssh/test/forward_unix_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd
 // +build aix darwin dragonfly freebsd linux netbsd openbsd
 
 package test
diff --git a/ssh/test/multi_auth_test.go b/ssh/test/multi_auth_test.go
index f594d36..da8f674 100644
--- a/ssh/test/multi_auth_test.go
+++ b/ssh/test/multi_auth_test.go
@@ -14,6 +14,7 @@
 // not exist these tests will be skipped. See compile instructions
 // (for linux) in file ./sshd_test_pw.c.
 
+//go:build linux
 // +build linux
 
 package test
diff --git a/ssh/test/session_test.go b/ssh/test/session_test.go
index e363869..d66509b 100644
--- a/ssh/test/session_test.go
+++ b/ssh/test/session_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows && !solaris && !js
 // +build !windows,!solaris,!js
 
 package test
diff --git a/ssh/test/test_unix_test.go b/ssh/test/test_unix_test.go
index cf62d42..dbd02c7 100644
--- a/ssh/test/test_unix_test.go
+++ b/ssh/test/test_unix_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || plan9
 // +build aix darwin dragonfly freebsd linux netbsd openbsd plan9
 
 package test