diff --git a/src/hb-open-type-private.hh b/src/hb-open-type-private.hh
index bdffa95..c66d707 100644
--- a/src/hb-open-type-private.hh
+++ b/src/hb-open-type-private.hh
@@ -254,7 +254,7 @@
 struct Sanitizer
 {
   static hb_blob_t *sanitize (hb_blob_t *blob) {
-    hb_sanitize_context_t context[1];
+    hb_sanitize_context_t context[1] = {{}};
     bool sane;
 
     /* TODO is_sane() stuff */