diff --git a/hw/core/loader.c b/hw/core/loader.c
index 4dd5a71fb7..b7bb44b7f7 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -558,7 +558,7 @@ static void zfree(void *x, void *addr)
 
 ssize_t gunzip(void *dst, size_t dstlen, uint8_t *src, size_t srclen)
 {
-    z_stream s;
+    z_stream s = {};
     ssize_t dstbytes;
     int r, i, flags;