The niothreadids struct field is size_t, so must use %zu not %lu with printf. While they're identical on some platforms, on others they are different, causing warnings conf/domain_conf.c: In function 'virDomainDefCheckABIStabilityFlags': conf/domain_conf.c:19575:26: error: format '%lu' expects argument of type 'long unsigned int', but argument 7 has type 'size_t {aka unsigned int}' [-Werror=format=] _("Target domain iothreads count %lu does not " ^ conf/domain_conf.c: In function 'virDomainDefFormatInternal': conf/domain_conf.c:23915:46: error: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'size_t {aka unsigned int}' [-Werror=format=] virBufferAsprintf(buf, "<iothreads>%lu</iothreads>\n", ^ Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com&gt; --- Pushed to fix Win32 builds src/conf/domain_conf.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index ea2cd0e..79bdbdf 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -19572,8 +19572,8 @@ virDomainDefCheckABIStabilityFlags(virDomainDefPtr src, if (src->niothreadids != dst->niothreadids) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, - _("Target domain iothreads count %lu does not " - "match source %lu"), + _("Target domain iothreads count %zu does not " + "match source %zu"), dst->niothreadids, src->niothreadids); goto error; } @@ -23912,7 +23912,7 @@ virDomainDefFormatInternal(virDomainDefPtr def, goto error; if (def->niothreadids > 0) { - virBufferAsprintf(buf, "<iothreads>%lu</iothreads>\n", + virBufferAsprintf(buf, "<iothreads>%zu</iothreads>\n", def->niothreadids); if (virDomainDefIothreadShouldFormat(def)) { virBufferAddLit(buf, "<iothreadids>\n"); -- 2.9.3