On amd64 and arm64 gsize is typedef'ed to unsigned long (64 bit wide). The "i" GVariant format string is for gint32 the g_variant_get() family of functions (g_variant_dict_lookup in this case).
Therefore we must initialize the gsize typed value to zero to make sure we don't end up with random memory in the upper bits.
Fixes 9c627f52
Closes #686 (closed)