diff --git a/test/minigzip.c b/test/minigzip.c
index 8317344..aa7ac7a 100644
--- a/test/minigzip.c
+++ b/test/minigzip.c
@@ -197,7 +197,7 @@ gzFile gz_open(path, fd, mode)
     gzFile gz;
     int ret;
 
-    gz = malloc(sizeof(gzFile));
+    gz = malloc(sizeof(struct gzFile_s));
     if (gz == NULL)
         return NULL;
     gz->write = strchr(mode, 'w') != NULL;