Index: mupdf/fitz/stm_filter.c
===================================================================
--- mupdf/fitz/stm_filter.c     (revision 1258)
+++ mupdf/fitz/stm_filter.c     (working copy)
@@ -22,7 +22,7 @@
        assert(out->wp <= out->ep);

        f->consumed = in->rp > oldrp;
-       f->produced = out->wp > oldwp;
+       f->produced = out->wp > oldwp && reason != fz_ioneedin;
        f->count += out->wp - oldwp;

        /* iodone or error */