diff --git a/src/IPS/Apply.hs b/src/IPS/Apply.hs
index d4c1bf5..6124ccd 100644
--- a/src/IPS/Apply.hs
+++ b/src/IPS/Apply.hs
@@ -20,7 +20,7 @@ unsafeApplyM p buf =
         let offset' = fromIntegral offset
         let sz = Vector.length bs
         let dst = MVector.slice offset' sz buf
-        Vector.unsafeCopy dst bs
+        Vector.copy dst bs
       RLE {size, value} -> do
         let offset' = fromIntegral offset
         let sz = fromIntegral size