diff --git a/include/minix/sys_config.h b/include/minix/sys_config.h
index 59a2115a9..69ccaa47d 100755
--- a/include/minix/sys_config.h
+++ b/include/minix/sys_config.h
@@ -20,6 +20,7 @@
 
 #define _NR_PROCS	100
 #define _NR_SYS_PROCS	32
+#define _NR_HOLES (2*_NR_PROCS+4)  /* No. of memory holes maintained by PM */
 
 /* Set the CHIP type based on the machine selected. The symbol CHIP is actually
  * indicative of more than just the CPU.  For example, machines for which
diff --git a/include/minix/type.h b/include/minix/type.h
index d992bd603..4760de0c0 100755
--- a/include/minix/type.h
+++ b/include/minix/type.h
@@ -47,6 +47,13 @@ struct vir_addr {
   vir_bytes offset;
 };
 
+/* Memory allocation by PM. */
+struct hole {
+  struct hole *h_next;          /* pointer to next entry on the list */
+  phys_clicks h_base;           /* where does the hole begin? */
+  phys_clicks h_len;            /* how big is the hole? */
+};
+
 #define phys_cp_req vir_cp_req 
 struct vir_cp_req {
   struct vir_addr src;