diff --git a/README.md b/README.md
index 6bd3383..3f11c87 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,10 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 
+### Using on macOS
+1. Install [homebrew](http://brew.sh/)
+2. `$ brew install openssl` or `$ brew install openssl@1.1`
+
 ### Using on Windows
 1. Install [mingw-w64](http://mingw-w64.sourceforge.net/)
 2. Install [pkg-config-lite](http://sourceforge.net/projects/pkgconfiglite)
diff --git a/bio.go b/bio.go
index b8d32e0..9242853 100644
--- a/bio.go
+++ b/bio.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/build.go b/build.go
index 94720e3..0c172da 100644
--- a/build.go
+++ b/build.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #cgo pkg-config: libssl libcrypto
diff --git a/cert.go b/cert.go
index 45754ac..a04d37a 100644
--- a/cert.go
+++ b/cert.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/ciphers.go b/ciphers.go
index f916b4c..1b4fde0 100644
--- a/ciphers.go
+++ b/ciphers.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/ciphers_gcm.go b/ciphers_gcm.go
index e21b2e5..97a7eda 100644
--- a/ciphers_gcm.go
+++ b/ciphers_gcm.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo,!darwin
-
 package openssl
 
 // #include <openssl/evp.h>
diff --git a/ciphers_test.go b/ciphers_test.go
index d1d430b..21132e2 100644
--- a/ciphers_test.go
+++ b/ciphers_test.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build !darwin
-
 package openssl
 
 import (
diff --git a/conn.go b/conn.go
index 3022829..05ecd81 100644
--- a/conn.go
+++ b/conn.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/ctx.go b/ctx.go
index ee6a3f8..3589c2a 100644
--- a/ctx.go
+++ b/ctx.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/dhparam.go b/dhparam.go
index 23b939f..1bdb28a 100644
--- a/dhparam.go
+++ b/dhparam.go
@@ -1,5 +1,3 @@
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/digest.go b/digest.go
index 77f159c..9b42eb9 100644
--- a/digest.go
+++ b/digest.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/engine.go b/engine.go
index 7a175b7..7d6d9bc 100644
--- a/engine.go
+++ b/engine.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 /*
diff --git a/fips.go b/fips.go
index b3a03fa..3ae4152 100644
--- a/fips.go
+++ b/fips.go
@@ -1,5 +1,3 @@
-// +build cgo
-
 package openssl
 
 /*
diff --git a/hmac.go b/hmac.go
index e12d5d9..3c75f70 100644
--- a/hmac.go
+++ b/hmac.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/hmac_test.go b/hmac_test.go
index 03b5d46..fcb55e0 100644
--- a/hmac_test.go
+++ b/hmac_test.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 import (
diff --git a/hostname.go b/hostname.go
index 8c3b8e8..93dedd4 100644
--- a/hostname.go
+++ b/hostname.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 /*
diff --git a/init.go b/init.go
index 48c71f2..7841c24 100644
--- a/init.go
+++ b/init.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 /*
 Package openssl is a light wrapper around OpenSSL for Go.
 
diff --git a/init_posix.go b/init_posix.go
index 559ac1e..2a187d5 100644
--- a/init_posix.go
+++ b/init_posix.go
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build linux darwin cgo
+// +build linux darwin
 // +build !windows
 
 package openssl
diff --git a/init_windows.go b/init_windows.go
index 6006996..32d498c 100644
--- a/init_windows.go
+++ b/init_windows.go
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build windows cgo
+// +build windows
 
 package openssl
 
diff --git a/key.go b/key.go
index e6f08c6..cf0b32f 100644
--- a/key.go
+++ b/key.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/mapping.go b/mapping.go
index 066aba6..8a806bf 100644
--- a/mapping.go
+++ b/mapping.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 import (
diff --git a/old_openssl_compat.go b/old_openssl_compat.go
deleted file mode 100644
index 028f13b..0000000
--- a/old_openssl_compat.go
+++ /dev/null
@@ -1,44 +0,0 @@
-// Copyright (C) 2014 Space Monkey, Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//   http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// +build !darwin brew
-// +build cgo
-
-package openssl
-
-// #include <openssl/ssl.h>
-import "C"
-
-// these constants do not exist in the openssl version packaged with os x. when
-// darwin decides to update the base openssl version, we can move these back
-// to the appropriate spots in the source. as a workaround, if you need access
-// to these constants on darwin, use homebrew or whatever to install a more
-// recent version of os x, and build the package with the '-tags brew' flag
-
-const (
-	UnsupportedConstraintSyntax VerifyResult = C.X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX
-	UnsupportedConstraintType   VerifyResult = C.X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE
-	UnsupportedExtensionFeature VerifyResult = C.X509_V_ERR_UNSUPPORTED_EXTENSION_FEATURE
-	ExcludedViolation           VerifyResult = C.X509_V_ERR_EXCLUDED_VIOLATION
-	SubtreeMinmax               VerifyResult = C.X509_V_ERR_SUBTREE_MINMAX
-	UnsupportedNameSyntax       VerifyResult = C.X509_V_ERR_UNSUPPORTED_NAME_SYNTAX
-	DifferentCrlScope           VerifyResult = C.X509_V_ERR_DIFFERENT_CRL_SCOPE
-	PermittedViolation          VerifyResult = C.X509_V_ERR_PERMITTED_VIOLATION
-	CrlPathValidationError      VerifyResult = C.X509_V_ERR_CRL_PATH_VALIDATION_ERROR
-)
-
-const (
-	NoTLSv1_1 Options = C.SSL_OP_NO_TLSv1_1
-	NoTLSv1_2 Options = C.SSL_OP_NO_TLSv1_2
-)
diff --git a/sha1.go b/sha1.go
index e479b80..bc7264e 100644
--- a/sha1.go
+++ b/sha1.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/sha1_test.go b/sha1_test.go
index 37037e4..0c37cf6 100644
--- a/sha1_test.go
+++ b/sha1_test.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 import (
diff --git a/sha256.go b/sha256.go
index 922f2f3..3444ace 100644
--- a/sha256.go
+++ b/sha256.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/sha256_test.go b/sha256_test.go
index 89df88a..6ed7b58 100644
--- a/sha256_test.go
+++ b/sha256_test.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 import (
diff --git a/ssl.go b/ssl.go
index eda530a..daf7af9 100644
--- a/ssl.go
+++ b/ssl.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"
diff --git a/tickets.go b/tickets.go
index 6000d27..c85b731 100644
--- a/tickets.go
+++ b/tickets.go
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build cgo
-
 package openssl
 
 // #include "shim.h"