diff --git a/m4/virt-compile-warnings.m4 b/m4/virt-compile-warnings.m4
index 27413b09f2..7e252d551a 100644
--- a/m4/virt-compile-warnings.m4
+++ b/m4/virt-compile-warnings.m4
@@ -62,7 +62,6 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[
         dontwarn="$dontwarn -Wcast-qual"
         dontwarn="$dontwarn -Wconversion"
         dontwarn="$dontwarn -Wsign-conversion"
-        dontwarn="$dontwarn -Wold-style-definition"
         dontwarn="$dontwarn -Wpacked"
         dontwarn="$dontwarn -Wunused-macros"
         dontwarn="$dontwarn -Woverlength-strings"
diff --git a/src/xen/xen_hypervisor.c b/src/xen/xen_hypervisor.c
index 47355ce951..8a9dae5afa 100644
--- a/src/xen/xen_hypervisor.c
+++ b/src/xen/xen_hypervisor.c
@@ -3621,7 +3621,7 @@ xenHypervisorGetVcpuMax(virDomainPtr domain)
  * Return true if the current process should be able to connect to Xen.
  */
 int
-xenHavePrivilege()
+xenHavePrivilege(void)
 {
 #ifdef __sun
     return priv_ineffect (PRIV_XVM_CONTROL);
diff --git a/tests/testutils.c b/tests/testutils.c
index 0ce3c7bf56..1f3b5693d4 100644
--- a/tests/testutils.c
+++ b/tests/testutils.c
@@ -457,14 +457,14 @@ virTestGetFlag(const char *name) {
 }
 
 unsigned int
-virTestGetDebug() {
+virTestGetDebug(void) {
     if (testDebug == -1)
         testDebug = virTestGetFlag("VIR_TEST_DEBUG");
     return testDebug;
 }
 
 unsigned int
-virTestGetVerbose() {
+virTestGetVerbose(void) {
     if (testVerbose == -1)
         testVerbose = virTestGetFlag("VIR_TEST_VERBOSE");
     return testVerbose || virTestGetDebug();