diff --git a/lib/stream.c b/lib/stream.c
index a50835e..821ad6e 100644
--- a/lib/stream.c
+++ b/lib/stream.c
@@ -99,7 +99,7 @@
       return NULL;
     }
   
-  s = XCALLOC (MTYPE_STREAM, offsetof(struct stream, size));
+  s = XCALLOC (MTYPE_STREAM, offsetof(struct stream, data[size]));
 
   if (s == NULL)
     return s;