diff --git a/tests/networkxml2firewalltest.c b/tests/networkxml2firewalltest.c
index e0244f508e..3496445f0d 100644
--- a/tests/networkxml2firewalltest.c
+++ b/tests/networkxml2firewalltest.c
@@ -60,8 +60,10 @@ VIR_MOCK_WRAP_RET_ARGS(g_dbus_connection_call_sync,
                        GCancellable *, cancellable,
                        GError **, error)
 {
-    if (parameters)
+    if (parameters) {
+        g_variant_ref_sink(parameters);
         g_variant_unref(parameters);
+    }
 
     VIR_MOCK_REAL_INIT(g_dbus_connection_call_sync);
 
diff --git a/tests/virfirewalltest.c b/tests/virfirewalltest.c
index 607638e9d0..646b999d96 100644
--- a/tests/virfirewalltest.c
+++ b/tests/virfirewalltest.c
@@ -79,6 +79,9 @@ VIR_MOCK_WRAP_RET_ARGS(g_dbus_connection_call_sync,
     GVariant *reply = NULL;
     g_autoptr(GVariant) params = parameters;
 
+    if (params)
+        g_variant_ref_sink(params);
+
     VIR_MOCK_REAL_INIT(g_dbus_connection_call_sync);
 
     if (STREQ(bus_name, "org.freedesktop.DBus") &&
diff --git a/tests/virpolkittest.c b/tests/virpolkittest.c
index 011d83a506..b7cbe28466 100644
--- a/tests/virpolkittest.c
+++ b/tests/virpolkittest.c
@@ -52,6 +52,9 @@ VIR_MOCK_WRAP_RET_ARGS(g_dbus_connection_call_sync,
     GVariant *reply = NULL;
     g_autoptr(GVariant) params = parameters;
 
+    if (params)
+        g_variant_ref_sink(params);
+
     VIR_MOCK_REAL_INIT(g_dbus_connection_call_sync);
 
     if (STREQ(bus_name, "org.freedesktop.PolicyKit1") &&
diff --git a/tests/virsystemdtest.c b/tests/virsystemdtest.c
index c1411d7c05..bd0ca51140 100644
--- a/tests/virsystemdtest.c
+++ b/tests/virsystemdtest.c
@@ -54,8 +54,10 @@ VIR_MOCK_WRAP_RET_ARGS(g_dbus_connection_call_sync,
 {
     GVariant *reply = NULL;
 
-    if (parameters)
+    if (parameters) {
+        g_variant_ref_sink(parameters);
         g_variant_unref(parameters);
+    }
 
     VIR_MOCK_REAL_INIT(g_dbus_connection_call_sync);