diff --git a/sys/dev/aac/aac_disk.c b/sys/dev/aac/aac_disk.c
index 1505a6adeec5..23287adcde09 100644
--- a/sys/dev/aac/aac_disk.c
+++ b/sys/dev/aac/aac_disk.c
@@ -219,8 +219,6 @@ static int
 aac_disk_attach(device_t dev)
 {
     struct aac_disk	*sc = (struct aac_disk *)device_get_softc(dev);
-    int			sgspace;
-    int			maxsg;
     
     debug_called(4);
 
@@ -258,16 +256,11 @@ aac_disk_attach(device_t dev)
     disks_registered++;
 #endif
 
-    /*
-     * We can calculate the maximum number of s/g entries based on the size of the
-     * FIB and the command structures packed within it.
+    /* 
+     * The adapters seem to have a 64K size limit on the max I/O size.  Set
+     * our size on accordance.
      */
-    sgspace = (sizeof(struct aac_fib) - sizeof(struct aac_fib_header) - 
-	       imax(sizeof(struct aac_blockwrite), sizeof(struct aac_blockread)));
-    maxsg = (sgspace - sizeof(struct aac_sg_table)) / sizeof(struct aac_sg_entry);
-	      
-    /* set the maximum I/O size to the theoretical worst maximum allowed by the S/G list size */
-    sc->ad_dev_t->si_iosize_max = (maxsg - 1) * PAGE_SIZE;
+    sc->ad_dev_t->si_iosize_max = 65536;
 
     return (0);
 }