diff --git a/util/mkimage.c b/util/mkimage.c
index 02944f28e..b94bfb781 100644
--- a/util/mkimage.c
+++ b/util/mkimage.c
@@ -1351,10 +1351,10 @@ grub_install_generate_image (const char *dir, const char *prefix,
 	    o->subsystem = grub_host_to_target16 (GRUB_PE32_SUBSYSTEM_EFI_APPLICATION);
 
 	    /* Do these really matter? */
-	    o->stack_reserve_size = grub_host_to_target64 (0x10000);
-	    o->stack_commit_size = grub_host_to_target64 (0x10000);
-	    o->heap_reserve_size = grub_host_to_target64 (0x10000);
-	    o->heap_commit_size = grub_host_to_target64 (0x10000);
+	    o->stack_reserve_size = grub_host_to_target32 (0x10000);
+	    o->stack_commit_size = grub_host_to_target32 (0x10000);
+	    o->heap_reserve_size = grub_host_to_target32 (0x10000);
+	    o->heap_commit_size = grub_host_to_target32 (0x10000);
     
 	    o->num_data_directories
 	      = grub_host_to_target32 (GRUB_PE32_NUM_DATA_DIRECTORIES);