diff --git a/README.md b/README.md
index ae401b3..e3a792b 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,10 @@ code for generating keys and utilizing multiple CPU threads for mining.
 
 `% go get -u -v git.tdem.in/tdemin/syg_go`
 
+This program contains some modded code from Yggdrasil that aims to improve
+performance. If you prefer to use original Yggdrasil code, set `-tags original`
+flag in the command above.
+
 ### History
 
 SimpleYggGen is originally a project by [@acetone](https://notabug.org/acetone),
diff --git a/crypto.go b/crypto.go
index 35a8af1..bf40398 100644
--- a/crypto.go
+++ b/crypto.go
@@ -5,6 +5,11 @@ import (
 	"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
 )
 
+// custom function selectors, see crypto_xxx.go
+var (
+	addrForNodeID func(*crypto.NodeID) *address.Address
+)
+
 // AddrForNodeID is a variant of Yggdrasil's src/address.AddrForNodeID that
 // might be slightly optimized for performance.
 //
diff --git a/crypto_original.go b/crypto_original.go
new file mode 100644
index 0000000..a0ed3dc
--- /dev/null
+++ b/crypto_original.go
@@ -0,0 +1,14 @@
+// +build original
+
+package main
+
+import (
+	"log"
+
+	"github.com/yggdrasil-network/yggdrasil-go/src/address"
+)
+
+func init() {
+	log.Println("using unmodified Yggdrasil code")
+	addrForNodeID = address.AddrForNodeID
+}
diff --git a/crypto_vendor.go b/crypto_vendor.go
new file mode 100644
index 0000000..5909965
--- /dev/null
+++ b/crypto_vendor.go
@@ -0,0 +1,10 @@
+// +build !original
+
+package main
+
+import "log"
+
+func init() {
+	log.Println("using vendored syg_go code")
+	addrForNodeID = AddrForNodeID
+}
diff --git a/main.go b/main.go
index da94066..8e81de3 100644
--- a/main.go
+++ b/main.go
@@ -73,7 +73,7 @@ func doBoxKeys(out chan<- keySet) {
 	for {
 		pub, priv := crypto.NewBoxKeys()
 		id := crypto.GetNodeID(pub)
-		ip := net.IP(AddrForNodeID(id)[:]).String()
+		ip := net.IP(addrForNodeID(id)[:]).String()
 		out <- keySet{priv[:], pub[:], id[:], ip}
 	}
 }