1 files changed, 4 insertions, 2 deletions

diff --git a/src/alloc.c b/src/alloc.c
index cf7778c05f6..7c461c5a6af 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -2701,8 +2701,10 @@ make_float (double float_value)
    GC are put on a free list to be reallocated before allocating
    any new cons cells from the latest cons_block.  */
 
-#define CONS_BLOCK_SIZE \
-  (((BLOCK_BYTES - sizeof (struct cons_block *)) * CHAR_BIT) \
+#define CONS_BLOCK_SIZE                                         \
+  (((BLOCK_BYTES - sizeof (struct cons_block *)                 \
+     /* The compiler might add padding at the end.  */          \
+     - (sizeof (struct Lisp_Cons) - sizeof (int))) * CHAR_BIT)  \
    / (sizeof (struct Lisp_Cons) * CHAR_BIT + 1))
 
 #define CONS_BLOCK(fptr) \