diff --git a/priv_key.go b/priv_key.go
index 74d5b5a3..efb85908 100644
--- a/priv_key.go
+++ b/priv_key.go
@@ -64,6 +64,8 @@ var privKeyMapper = data.NewMapper(PrivKey{}).
 
 //-------------------------------------
 
+var _ PrivKeyInner = PrivKeyEd25519{}
+
 // Implements PrivKey
 type PrivKeyEd25519 [64]byte
 
@@ -149,6 +151,8 @@ func GenPrivKeyEd25519FromSecret(secret []byte) PrivKeyEd25519 {
 
 //-------------------------------------
 
+var _ PrivKeyInner = PrivKeySecp256k1{}
+
 // Implements PrivKey
 type PrivKeySecp256k1 [32]byte
 
diff --git a/pub_key.go b/pub_key.go
index e6567d34..4de7d59c 100644
--- a/pub_key.go
+++ b/pub_key.go
@@ -67,6 +67,8 @@ var pubKeyMapper = data.NewMapper(PubKey{}).
 
 //-------------------------------------
 
+var _ PubKeyInner = PubKeyEd25519{}
+
 // Implements PubKeyInner
 type PubKeyEd25519 [32]byte
 
@@ -146,6 +148,8 @@ func (pubKey PubKeyEd25519) Wrap() PubKey {
 
 //-------------------------------------
 
+var _ PubKeyInner = PubKeySecp256k1{}
+
 // Implements PubKey.
 // Compressed pubkey (just the x-cord),
 // prefixed with 0x02 or 0x03, depending on the y-cord.
diff --git a/signature.go b/signature.go
index 66c9a8a2..5a165dc4 100644
--- a/signature.go
+++ b/signature.go
@@ -62,6 +62,8 @@ var sigMapper = data.NewMapper(Signature{}).
 
 //-------------------------------------
 
+var _ SignatureInner = SignatureEd25519{}
+
 // Implements Signature
 type SignatureEd25519 [64]byte
 
@@ -100,6 +102,8 @@ func (sig SignatureEd25519) Wrap() Signature {
 
 //-------------------------------------
 
+var _ SignatureInner = SignatureSecp256k1{}
+
 // Implements Signature
 type SignatureSecp256k1 []byte