diff --git a/src/config_gram.y b/src/config_gram.y
index bdea3352..6f6f8765 100644
--- a/src/config_gram.y
+++ b/src/config_gram.y
@@ -800,6 +800,13 @@ part_parm :
     }
   } |
 
+  K_PP_CONTROLSTACK TKN_EQUAL K_NULL {
+    {
+      current_part->ctl_stack_type = CTL_STACK_NONE;
+      memset(current_part->controlstack, 0, CTL_STACK_SIZE);
+    }
+  } |
+
   K_HVSP_CONTROLSTACK TKN_EQUAL num_list {
     {
       TOKEN * t;
@@ -831,6 +838,13 @@ part_parm :
     }
   } |
 
+  K_HVSP_CONTROLSTACK TKN_EQUAL K_NULL {
+    {
+      current_part->ctl_stack_type = CTL_STACK_NONE;
+      memset(current_part->controlstack, 0, CTL_STACK_SIZE);
+    }
+  } |
+
   K_FLASH_INSTR TKN_EQUAL num_list {
     {
       TOKEN * t;
@@ -861,6 +875,12 @@ part_parm :
     }
   } |
 
+  K_FLASH_INSTR TKN_EQUAL K_NULL {
+    {
+      memset(current_part->flash_instr, 0, FLASH_INSTR_SIZE);
+    }
+  } |
+
   K_EEPROM_INSTR TKN_EQUAL num_list {
     {
       TOKEN * t;
@@ -891,6 +911,12 @@ part_parm :
     }
   } |
 
+  K_EEPROM_INSTR TKN_EQUAL K_NULL {
+    {
+      memset(current_part->eeprom_instr, 0, EEPROM_INSTR_SIZE);
+    }
+  } |
+
   K_CHIP_ERASE_DELAY TKN_EQUAL TKN_NUMBER
     {
       current_part->chip_erase_delay = $3->value.number;
diff --git a/src/developer_opts.c b/src/developer_opts.c
index 482ece7d..5784b64f 100644
--- a/src/developer_opts.c
+++ b/src/developer_opts.c
@@ -363,13 +363,13 @@ static const char *dev_controlstack_name(AVRPART *p) {
   return
     p->ctl_stack_type == CTL_STACK_PP? "pp_controlstack":
     p->ctl_stack_type == CTL_STACK_HVSP? "hvsp_controlstack":
-    p->ctl_stack_type == CTL_STACK_NONE? "NONE":
+    p->ctl_stack_type == CTL_STACK_NONE? "NULL":
     "unknown_controlstack";
 }
 
 
 static void dev_stack_out(bool tsv, AVRPART *p, const char *name, unsigned char *stack, int ns) {
-  if(!strcmp(name, "NONE")) {
+  if(!strcmp(name, "NULL")) {
     name = "pp_controlstack";
     ns = 0;
   }