diff --git a/lib/common/output_html.c b/lib/common/output_html.c
index c8f0088..fc06641 100644
--- a/lib/common/output_html.c
+++ b/lib/common/output_html.c
@@ -72,6 +72,7 @@ html_free_priv(pcmk__output_t *out) {
     g_queue_free(priv->parent_q);
     g_slist_free(priv->errors);
     free(priv);
+    out->priv = NULL;
 }
 
 static bool
diff --git a/lib/common/output_log.c b/lib/common/output_log.c
index 5b45ce4..0208046 100644
--- a/lib/common/output_log.c
+++ b/lib/common/output_log.c
@@ -44,6 +44,7 @@ log_free_priv(pcmk__output_t *out) {
 
     g_queue_free(priv->prefixes);
     free(priv);
+    out->priv = NULL;
 }
 
 static bool
diff --git a/lib/common/output_text.c b/lib/common/output_text.c
index 54c409a..8f15849 100644
--- a/lib/common/output_text.c
+++ b/lib/common/output_text.c
@@ -43,6 +43,7 @@ text_free_priv(pcmk__output_t *out) {
 
     g_queue_free(priv->parent_q);
     free(priv);
+    out->priv = NULL;
 }
 
 static bool
diff --git a/lib/common/output_xml.c b/lib/common/output_xml.c
index 8565bfe..858da3f 100644
--- a/lib/common/output_xml.c
+++ b/lib/common/output_xml.c
@@ -54,6 +54,7 @@ xml_free_priv(pcmk__output_t *out) {
     g_queue_free(priv->parent_q);
     g_slist_free(priv->errors);
     free(priv);
+    out->priv = NULL;
 }
 
 static bool
diff --git a/tools/crm_mon_curses.c b/tools/crm_mon_curses.c
index 896fd98..b1129ba 100644
--- a/tools/crm_mon_curses.c
+++ b/tools/crm_mon_curses.c
@@ -46,6 +46,7 @@ curses_free_priv(pcmk__output_t *out) {
 
     g_queue_free(priv->parent_q);
     free(priv);
+    out->priv = NULL;
 }
 
 static bool