1 files changed, 2 insertions, 1 deletions
diff --git a/gzread.c b/gzread.c
index 8ace830..52985c9 100644
--- a/gzread.c
+++ b/gzread.c
@@ -58,7 +58,8 @@ local int gz_avail(state)
         return -1;
     if (state->eof == 0) {
         if (strm->avail_in) {       /* copy what's there to the start */
-            unsigned char *p = state->in, *q = strm->next_in;
+            unsigned char *p = state->in;
+            unsigned const char *q = strm->next_in;
             unsigned n = strm->avail_in;
             do {
                 *p++ = *q++;