diff --git a/src/test/test_hs_descriptor.c b/src/test/test_hs_descriptor.c
index 4889281cb1..90f2be2906 100644
--- a/src/test/test_hs_descriptor.c
+++ b/src/test/test_hs_descriptor.c
@@ -675,6 +675,8 @@ test_decode_bad_signature(void *arg)
 
   (void) arg;
 
+  memset(&desc_plaintext, 0, sizeof(desc_plaintext));
+
   /* Update approx time to dodge cert expiration */
   update_approx_time(1502661599);