diff --git a/applypatch/imgpatch.cpp b/applypatch/imgpatch.cpp
index ae6071f..00ea90e 100644
--- a/applypatch/imgpatch.cpp
+++ b/applypatch/imgpatch.cpp
@@ -160,7 +160,7 @@
         strm.zfree = Z_NULL;
         strm.opaque = Z_NULL;
         strm.avail_in = src_len;
-        strm.next_in = const_cast<unsigned char*>(old_data + src_start);
+        strm.next_in = old_data + src_start;
         strm.avail_out = expanded_len;
         strm.next_out = expanded_source.data();