diff --git a/lib/hx509/lock.c b/lib/hx509/lock.c
index 219a30192..07e9d3612 100644
--- a/lib/hx509/lock.c
+++ b/lib/hx509/lock.c
@@ -214,10 +214,12 @@ hx509_lock_prompt(hx509_lock lock, hx509_prompt *prompt)
 void
 hx509_lock_free(hx509_lock lock)
 {
-    hx509_certs_free(&lock->certs);
-    hx509_lock_reset_passwords(lock);
-    memset(lock, 0, sizeof(*lock));
-    free(lock);
+    if (lock) {
+	hx509_certs_free(&lock->certs);
+	hx509_lock_reset_passwords(lock);
+	memset(lock, 0, sizeof(*lock));
+	free(lock);
+    }
 }
 
 int