diff --git a/ecdsa.go b/ecdsa.go
index 0518ed1..2f59a22 100644
--- a/ecdsa.go
+++ b/ecdsa.go
@@ -69,7 +69,7 @@ func (m *SigningMethodECDSA) Verify(signingString, signature string, key interfa
 	case *ecdsa.PublicKey:
 		ecdsaKey = k
 	default:
-		return ErrInvalidKey
+		return ErrInvalidKeyType
 	}
 
 	if len(sig) != 2*m.KeySize {
@@ -103,7 +103,7 @@ func (m *SigningMethodECDSA) Sign(signingString string, key interface{}) (string
 	case *ecdsa.PrivateKey:
 		ecdsaKey = k
 	default:
-		return "", ErrInvalidKey
+		return "", ErrInvalidKeyType
 	}
 
 	// Create the hasher
diff --git a/errors.go b/errors.go
index 2e53f5d..d4b183c 100644
--- a/errors.go
+++ b/errors.go
@@ -6,7 +6,8 @@ import (
 
 // Error constants
 var (
-	ErrInvalidKey      = errors.New("key is invalid or of invalid type")
+	ErrInvalidKey      = errors.New("key is invalid")
+	ErrInvalidKeyType  = errors.New("key is of invalid type")
 	ErrHashUnavailable = errors.New("the requested hash function is unavailable")
 )
 
diff --git a/hmac.go b/hmac.go
index 192e625..c229919 100644
--- a/hmac.go
+++ b/hmac.go
@@ -49,7 +49,7 @@ func (m *SigningMethodHMAC) Verify(signingString, signature string, key interfac
 	// Verify the key is the right type
 	keyBytes, ok := key.([]byte)
 	if !ok {
-		return ErrInvalidKey
+		return ErrInvalidKeyType
 	}
 
 	// Decode signature, for comparison
diff --git a/rsa.go b/rsa.go
index ceb80f6..0ae0b19 100644
--- a/rsa.go
+++ b/rsa.go
@@ -58,7 +58,7 @@ func (m *SigningMethodRSA) Verify(signingString, signature string, key interface
 	var ok bool
 
 	if rsaKey, ok = key.(*rsa.PublicKey); !ok {
-		return ErrInvalidKey
+		return ErrInvalidKeyType
 	}
 
 	// Create hasher
diff --git a/rsa_pss.go b/rsa_pss.go
index b5b7073..10ee9db 100644
--- a/rsa_pss.go
+++ b/rsa_pss.go
@@ -106,7 +106,7 @@ func (m *SigningMethodRSAPSS) Sign(signingString string, key interface{}) (strin
 	case *rsa.PrivateKey:
 		rsaKey = k
 	default:
-		return "", ErrInvalidKey
+		return "", ErrInvalidKeyType
 	}
 
 	// Create the hasher