(VECSIZE): Round up when dividing.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 9fe189f36f5..ce48018d1ce 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -550,9 +550,10 @@ struct Lisp_String
   };
 
 /* If a struct is made to look like a vector, this macro returns the length
-   of that vector.  */
-#define VECSIZE(type) ((sizeof (type) - (sizeof (struct Lisp_Vector)    \
-                                         - sizeof (Lisp_Object)))       \
+   of the shortest vector that would hold that struct.  */
+#define VECSIZE(type) ((sizeof (type) - (sizeof (struct Lisp_Vector)  \
+                                         - sizeof (Lisp_Object))      \
+                        + sizeof(Lisp_Object) - 1) /* round up */     \
                        / sizeof (Lisp_Object))
 
 struct Lisp_Vector