diff --git a/src/lisp/x86-arch.h b/src/lisp/x86-arch.h
index 3283cce5ad9f20814da91a488e589f0d8725a4ae..bc9f640395017e2a2b8dede846f6a974ee5a9231 100644
--- a/src/lisp/x86-arch.h
+++ b/src/lisp/x86-arch.h
@@ -17,15 +17,13 @@ extern boolean os_support_sse2(void);
 #define FPU_STATE_SIZE 27
 
 /* 
- * Need 512 byte area, aligned on a 16-byte boundary.  So allocate
- * 512+16 bytes of space and let the routine adjust the appropriate
- * alignment.
+ * Need 512 byte area, aligned on a 16-byte boundary.
  */
 #define SSE_STATE_SIZE 512
 
 /*
  * Just use the SSE size for both x87 and sse2 since the SSE size is
- * enough for either.
+ * enough for either.  Make sure it's on a 16-byte boundary.
  */
 #define FPU_STATE(name)    u_int8_t name[SSE_STATE_SIZE] __attribute__((aligned(16)))