diff --git a/Data/X509/PublicKey.hs b/Data/X509/PublicKey.hs
--- a/Data/X509/PublicKey.hs
+++ b/Data/X509/PublicKey.hs
@@ -47,9 +47,9 @@
 instance ASN1Object PubKey where
     fromASN1 (Start Sequence:Start Sequence:OID pkalg:xs)
         | pkalg == getObjectID PubKeyALG_RSA =
-            case xs of
-                Null:End Sequence:BitString bits:End Sequence:xs2 -> decodeASN1Err "RSA" bits xs2 (toPubKeyRSA . fromASN1)
-                _ -> Left "fromASN1: X509.PubKey: unknown RSA format"
+            case removeNull xs of
+                End Sequence:BitString bits:End Sequence:xs2 -> decodeASN1Err "RSA" bits xs2 (toPubKeyRSA . fromASN1)
+                _ -> Left ("fromASN1: X509.PubKey: unknown RSA format: " ++ show xs)
         | pkalg == getObjectID PubKeyALG_DSA   =
             case xs of
                 Start Sequence:IntVal p:IntVal q:IntVal g:End Sequence:End Sequence:BitString bits:End Sequence:xs2 ->
@@ -79,6 +79,9 @@
                                     Left err -> Left err
                                     Right (r, xsinner) -> Right (r, xsinner ++ xs2)
             toPubKeyRSA = either Left (\(rsaKey, r) -> Right (PubKeyRSA rsaKey, r))
+
+            removeNull (Null:xs) = xs
+            removeNull l         = l
 
     fromASN1 l = Left ("fromASN1: X509.PubKey: unknown format:" ++ show l)
     toASN1 a = \xs -> encodePK a ++ xs
diff --git a/x509.cabal b/x509.cabal
--- a/x509.cabal
+++ b/x509.cabal
@@ -1,5 +1,5 @@
 Name:                x509
-Version:             1.4.9
+Version:             1.4.10
 Description:         X509 reader and writer
 License:             BSD3
 License-file:        LICENSE