1 files changed, 1 insertions, 1 deletions

diff --git a/compress.c b/compress.c
index ea4dfbe..6e97626 100644
--- a/compress.c
+++ b/compress.c
@@ -29,7 +29,7 @@ int ZEXPORT compress2 (dest, destLen, source, sourceLen, level)
     z_stream stream;
     int err;
 
-    stream.next_in = (Bytef*)source;
+    stream.next_in = (z_const Bytef *)source;
     stream.avail_in = (uInt)sourceLen;
 #ifdef MAXSEG_64K
     /* Check for source > 64K on 16-bit machine: */