diff --git a/subprojects/gst-devtools/validate/gst/validate/gst-validate-runner.c b/subprojects/gst-devtools/validate/gst/validate/gst-validate-runner.c
index f4af85e6a4..7121d526fb 100644
--- a/subprojects/gst-devtools/validate/gst/validate/gst-validate-runner.c
+++ b/subprojects/gst-devtools/validate/gst/validate/gst-validate-runner.c
@@ -445,6 +445,7 @@ gst_validate_runner_init (GstValidateRunner * runner)
 {
   runner->priv = gst_validate_runner_get_instance_private (runner);
 
+  g_mutex_init (&runner->priv->mutex);
   runner->priv->reports_by_type = g_hash_table_new (g_direct_hash,
       g_direct_equal);