diff --git a/p2p/pex/errors.go b/p2p/pex/errors.go
new file mode 100644
index 000000000..6d5451e3f
--- /dev/null
+++ b/p2p/pex/errors.go
@@ -0,0 +1,41 @@
+package pex
+
+import (
+	"fmt"
+
+	"github.com/tendermint/tendermint/p2p"
+)
+
+type ErrAddrBookNonRoutable struct {
+	Addr *p2p.NetAddress
+}
+
+func (err ErrAddrBookNonRoutable) Error() string {
+	return fmt.Sprintf("Cannot add non-routable address %v", err.Addr)
+}
+
+type ErrAddrBookSelf struct {
+	Addr *p2p.NetAddress
+}
+
+func (err ErrAddrBookSelf) Error() string {
+	return fmt.Sprintf("Cannot add ourselves with address %v", err.Addr)
+}
+
+type ErrAddrBookNilAddr struct {
+	Addr *p2p.NetAddress
+	Src  *p2p.NetAddress
+}
+
+func (err ErrAddrBookNilAddr) Error() string {
+	return fmt.Sprintf("Cannot add a nil address. Got (addr, src) = (%v, %v)", err.Addr, err.Src)
+}
+
+type ErrAddrBookFull struct {
+	Addr *p2p.NetAddress
+	Size int
+}
+
+func (err ErrAddrBookFull) Error() string {
+	return fmt.Sprintf("Can't add new address (%v), addr book is full (%d)", err.Addr, err.Size)
+}