diff --git a/Data/ASN1/Get.hs b/Data/ASN1/Get.hs
--- a/Data/ASN1/Get.hs
+++ b/Data/ASN1/Get.hs
@@ -33,7 +33,6 @@
 import Foreign
 
 import qualified Data.ByteString          as B
-import qualified Data.ByteString.Unsafe   as B
 
 -- | The result of a parse.
 data Result r = Fail String
@@ -185,13 +184,17 @@
 
 -- | Pull @n@ bytes from the input, as a strict ByteString.
 getBytes :: Int -> Get B.ByteString
-getBytes n = do
-     s <- ensure n
-     put (fromIntegral n) $ B.unsafeDrop n s
-     return $ B.unsafeTake n s
+getBytes n
+  | n <= 0    = return B.empty
+  | otherwise = do
+    s <- ensure n
+    let (b1, b2) = B.splitAt n s
+    put (fromIntegral n) b2
+    return b1
 
 getWord8 :: Get Word8
 getWord8 = do
-     s <- ensure 1
-     put 1 $ B.unsafeTail s
-     return $ B.unsafeHead s
+    s <- ensure 1
+    case B.uncons s of
+        Nothing     -> error "getWord8: ensure internal error"
+        Just (h,b2) -> put 1 b2 >> return h
diff --git a/asn1-encoding.cabal b/asn1-encoding.cabal
--- a/asn1-encoding.cabal
+++ b/asn1-encoding.cabal
@@ -1,5 +1,5 @@
 Name:                asn1-encoding
-Version:             0.9.3
+Version:             0.9.4
 Synopsis:            ASN1 data reader and writer in RAW, BER and DER forms
 Description:
     ASN1 data reader and writer in raw form with supports for high level forms of ASN1 (BER, and DER).