--- src/alloc.c~	2003-01-17 14:45:13.000000000 +0100
+++ src/alloc.c	2007-04-29 12:32:43.000000000 +0200
@@ -3716,7 +3716,10 @@
 static void
 mark_stack ()
 {
-  jmp_buf j;
+  union aligned_jmpbuf {
+    Lisp_Object o;
+    jmp_buf j;
+  } j;
   volatile int stack_grows_down_p = (char *) &j > (char *) stack_base;
   void *end;
 
@@ -3744,7 +3747,7 @@
     }
 #endif /* GC_SETJMP_WORKS */
   
-  setjmp (j);
+  setjmp (j.j);
   end = stack_grows_down_p ? (char *) &j + sizeof j : (char *) &j;
 #endif /* not GC_SAVE_REGISTERS_ON_STACK */