diff --git a/zlib/inflate.c b/zlib/inflate.c

index e43abd9..bd33c19 100644

--- a/zlib/inflate.c

+++ b/zlib/inflate.c

@@ -740,8 +740,9 @@ int flush;

                 if (copy > have) copy = have;

                 if (copy) {

                     if (state->head != Z_NULL &&

-                        state->head->extra != Z_NULL) {

-                        len = state->head->extra_len - state->length;

+                        state->head->extra != Z_NULL &&

+                        (len = state->head->extra_len - state->length) <

+			    state->head->extra_max) {

                         zmemcpy(state->head->extra + len, next,

                                 len + copy > state->head->extra_max ?

                                 state->head->extra_max - len : copy);