diff --git a/arch/8051/src/up_idle.c b/arch/8051/src/up_idle.c
index 4259f8a74b7..e06046c0cdb 100644
--- a/arch/8051/src/up_idle.c
+++ b/arch/8051/src/up_idle.c
@@ -1,4 +1,4 @@
-/************************************************************
+/************************************************************************
  * up_idle.c
  *
  *   Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
@@ -33,7 +33,7 @@
  *
  ************************************************************************/
 
-/************************************************************
+/************************************************************************
  * Included Files
  ************************************************************************/
 
@@ -44,27 +44,27 @@
 
 #include "up_internal.h"
 
-/************************************************************
- * Private Definitions
+/************************************************************************
+ * Pre-processor Definitions
  ************************************************************************/
 
-/************************************************************
+/************************************************************************
  * Private Data
  ************************************************************************/
 
 #if defined(CONFIG_ARCH_LEDS) && defined(CONFIG_ARCH_BRINGUP)
-static /**************** g_ledtoggle = 0;
+static uint8_t g_ledtoggle = 0;
 #endif
 
-/************************************************************
+/************************************************************************
  * Private Functions
  ************************************************************************/
 
-/************************************************************
+/************************************************************************
  * Public Functions
  ************************************************************************/
 
-/************************************************************
+/************************************************************************
  * Name: up_idle
  *
  * Description:
@@ -93,4 +93,3 @@ void up_idle(void)
     }
 #endif
 }
-
diff --git a/arch/arm/src/common/up_createstack.c b/arch/arm/src/common/up_createstack.c
index b17e13b5b87..efa0e0a1576 100644
--- a/arch/arm/src/common/up_createstack.c
+++ b/arch/arm/src/common/up_createstack.c
@@ -136,7 +136,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
@@ -149,9 +149,9 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
        */
 
 #if defined(CONFIG_DEBUG) && !defined(CONFIG_DEBUG_STACK)
-      tcb->stack_alloc_ptr = (uint32_t *)kzalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kuzalloc(stack_size);
 #else
-      tcb->stack_alloc_ptr = (uint32_t *)kmalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kumalloc(stack_size);
 #endif
 #ifdef CONFIG_DEBUG
       if (!tcb->stack_alloc_ptr)
diff --git a/arch/arm/src/common/up_releasestack.c b/arch/arm/src/common/up_releasestack.c
index cb0bf030ade..94311b20c31 100644
--- a/arch/arm/src/common/up_releasestack.c
+++ b/arch/arm/src/common/up_releasestack.c
@@ -71,7 +71,7 @@ void up_release_stack(struct tcb_s *dtcb)
 {
   if (dtcb->stack_alloc_ptr)
     {
-      sched_free(dtcb->stack_alloc_ptr);
+      sched_ufree(dtcb->stack_alloc_ptr);
       dtcb->stack_alloc_ptr = NULL;
     }
 
diff --git a/arch/arm/src/common/up_usestack.c b/arch/arm/src/common/up_usestack.c
index d94f99a5756..57eb1d36ea9 100644
--- a/arch/arm/src/common/up_usestack.c
+++ b/arch/arm/src/common/up_usestack.c
@@ -116,7 +116,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 
   if (tcb->stack_alloc_ptr)
     {
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
     }
 
   /* Save the stack allocation */
diff --git a/arch/avr/src/avr/up_createstack.c b/arch/avr/src/avr/up_createstack.c
index aed449f8234..1eb56f918e1 100644
--- a/arch/avr/src/avr/up_createstack.c
+++ b/arch/avr/src/avr/up_createstack.c
@@ -95,7 +95,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
@@ -108,9 +108,9 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
        */
 
 #if defined(CONFIG_DEBUG) && !defined(CONFIG_DEBUG_STACK)
-      tcb->stack_alloc_ptr = (FAR void *)kzalloc(stack_size);
+      tcb->stack_alloc_ptr = (FAR void *)kuzalloc(stack_size);
 #else
-      tcb->stack_alloc_ptr = (FAR void *)kmalloc(stack_size);
+      tcb->stack_alloc_ptr = (FAR void *)kumalloc(stack_size);
 #endif
 #ifdef CONFIG_DEBUG
       if (!tcb->stack_alloc_ptr)
diff --git a/arch/avr/src/avr/up_usestack.c b/arch/avr/src/avr/up_usestack.c
index cd93f5d23c3..22bdcf84e1c 100644
--- a/arch/avr/src/avr/up_usestack.c
+++ b/arch/avr/src/avr/up_usestack.c
@@ -92,7 +92,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
     }
 
   /* Save the stack allocation */
diff --git a/arch/avr/src/avr32/up_createstack.c b/arch/avr/src/avr32/up_createstack.c
index bfe87743f39..5d49f497786 100644
--- a/arch/avr/src/avr32/up_createstack.c
+++ b/arch/avr/src/avr32/up_createstack.c
@@ -94,7 +94,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
@@ -107,9 +107,9 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
        */
 
 #if defined(CONFIG_DEBUG) && !defined(CONFIG_DEBUG_STACK)
-      tcb->stack_alloc_ptr = (FAR void *)kzalloc(stack_size);
+      tcb->stack_alloc_ptr = (FAR void *)kuzalloc(stack_size);
 #else
-      tcb->stack_alloc_ptr = (FAR void *)kmalloc(stack_size);
+      tcb->stack_alloc_ptr = (FAR void *)kumalloc(stack_size);
 #endif
 #ifdef CONFIG_DEBUG
       if (!tcb->stack_alloc_ptr)
diff --git a/arch/avr/src/avr32/up_usestack.c b/arch/avr/src/avr32/up_usestack.c
index 5afadb922d8..43dc6bfe9c0 100644
--- a/arch/avr/src/avr32/up_usestack.c
+++ b/arch/avr/src/avr32/up_usestack.c
@@ -89,7 +89,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 
   if (tcb->stack_alloc_ptr)
     {
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
     }
 
   /* Save the stack allocation */
diff --git a/arch/avr/src/common/up_releasestack.c b/arch/avr/src/common/up_releasestack.c
index 98b1faea104..afce3261db2 100644
--- a/arch/avr/src/common/up_releasestack.c
+++ b/arch/avr/src/common/up_releasestack.c
@@ -71,7 +71,7 @@ void up_release_stack(struct tcb_s *dtcb)
 {
   if (dtcb->stack_alloc_ptr)
     {
-      sched_free(dtcb->stack_alloc_ptr);
+      sched_ufree(dtcb->stack_alloc_ptr);
       dtcb->stack_alloc_ptr = NULL;
     }
 
diff --git a/arch/hc/src/common/up_createstack.c b/arch/hc/src/common/up_createstack.c
index 272c4e849fa..d5d5a853a66 100644
--- a/arch/hc/src/common/up_createstack.c
+++ b/arch/hc/src/common/up_createstack.c
@@ -91,7 +91,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
@@ -104,9 +104,9 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
        */
 
 #if defined(CONFIG_DEBUG) && !defined(CONFIG_DEBUG_STACK)
-      tcb->stack_alloc_ptr = (uint32_t *)kzalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kuzalloc(stack_size);
 #else
-      tcb->stack_alloc_ptr = (uint32_t *)kmalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kumalloc(stack_size);
 #endif
 #ifdef CONFIG_DEBUG
       if (!tcb->stack_alloc_ptr)
diff --git a/arch/hc/src/common/up_releasestack.c b/arch/hc/src/common/up_releasestack.c
index 3d8b6117688..f6eaec982fc 100644
--- a/arch/hc/src/common/up_releasestack.c
+++ b/arch/hc/src/common/up_releasestack.c
@@ -72,7 +72,7 @@ void up_release_stack(struct tcb_s *dtcb)
 {
   if (dtcb->stack_alloc_ptr)
     {
-      sched_free(dtcb->stack_alloc_ptr);
+      sched_ufree(dtcb->stack_alloc_ptr);
       dtcb->stack_alloc_ptr = NULL;
     }
 
diff --git a/arch/hc/src/common/up_usestack.c b/arch/hc/src/common/up_usestack.c
index 53a571ed4ba..f23677be529 100644
--- a/arch/hc/src/common/up_usestack.c
+++ b/arch/hc/src/common/up_usestack.c
@@ -87,7 +87,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 
   if (tcb->stack_alloc_ptr && tcb->adj_stack_size != stack_size)
     {
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
diff --git a/arch/mips/src/common/up_createstack.c b/arch/mips/src/common/up_createstack.c
index 02cdd83d721..e4689fc7c9a 100644
--- a/arch/mips/src/common/up_createstack.c
+++ b/arch/mips/src/common/up_createstack.c
@@ -112,7 +112,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
@@ -125,9 +125,9 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
        */
 
 #if defined(CONFIG_DEBUG) && !defined(CONFIG_DEBUG_STACK)
-      tcb->stack_alloc_ptr = (uint32_t *)kzalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kuzalloc(stack_size);
 #else
-      tcb->stack_alloc_ptr = (uint32_t *)kmalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kumalloc(stack_size);
 #endif
 #ifdef CONFIG_DEBUG
       if (!tcb->stack_alloc_ptr)
diff --git a/arch/mips/src/common/up_releasestack.c b/arch/mips/src/common/up_releasestack.c
index 7cbeb86e7e2..d507c3b7b47 100644
--- a/arch/mips/src/common/up_releasestack.c
+++ b/arch/mips/src/common/up_releasestack.c
@@ -71,7 +71,7 @@ void up_release_stack(struct tcb_s *dtcb)
 {
   if (dtcb->stack_alloc_ptr)
     {
-      sched_free(dtcb->stack_alloc_ptr);
+      sched_ufree(dtcb->stack_alloc_ptr);
       dtcb->stack_alloc_ptr = NULL;
     }
 
diff --git a/arch/mips/src/common/up_usestack.c b/arch/mips/src/common/up_usestack.c
index 6fa521579e0..208c15bc04d 100644
--- a/arch/mips/src/common/up_usestack.c
+++ b/arch/mips/src/common/up_usestack.c
@@ -89,7 +89,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 
   if (tcb->stack_alloc_ptr)
     {
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
     }
 
   /* Save the stack allocation */
diff --git a/arch/rgmp/src/nuttx.c b/arch/rgmp/src/nuttx.c
index 63e925b8cfb..0a13401c20c 100644
--- a/arch/rgmp/src/nuttx.c
+++ b/arch/rgmp/src/nuttx.c
@@ -123,7 +123,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
 
     /* Allocate the memory for the stack */
 
-    uint32_t *stack_alloc_ptr = (uint32_t*)kmalloc(adj_stack_size);
+    uint32_t *stack_alloc_ptr = (uint32_t*)kumalloc(adj_stack_size);
     if (stack_alloc_ptr) {
 		/* This is the address of the last word in the allocation */
 
@@ -161,7 +161,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 void up_release_stack(struct tcb_s *dtcb)
 {
     if (dtcb->stack_alloc_ptr) {
-		kfree(dtcb->stack_alloc_ptr);
+		kufree(dtcb->stack_alloc_ptr);
     }
 
     dtcb->stack_alloc_ptr = NULL;
diff --git a/arch/sh/src/common/up_createstack.c b/arch/sh/src/common/up_createstack.c
index 296245a4943..9abc05f76da 100644
--- a/arch/sh/src/common/up_createstack.c
+++ b/arch/sh/src/common/up_createstack.c
@@ -91,7 +91,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
@@ -104,9 +104,9 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
        */
 
 #if defined(CONFIG_DEBUG) && !defined(CONFIG_DEBUG_STACK)
-      tcb->stack_alloc_ptr = (uint32_t *)kzalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kuzalloc(stack_size);
 #else
-      tcb->stack_alloc_ptr = (uint32_t *)kmalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kumalloc(stack_size);
 #endif
 #ifdef CONFIG_DEBUG
       if (!tcb->stack_alloc_ptr)
diff --git a/arch/sh/src/common/up_releasestack.c b/arch/sh/src/common/up_releasestack.c
index 3b4e4c91436..a8b9d7769da 100644
--- a/arch/sh/src/common/up_releasestack.c
+++ b/arch/sh/src/common/up_releasestack.c
@@ -71,7 +71,7 @@ void up_release_stack(struct tcb_s *dtcb)
 {
   if (dtcb->stack_alloc_ptr)
     {
-      sched_free(dtcb->stack_alloc_ptr);
+      sched_ufree(dtcb->stack_alloc_ptr);
       dtcb->stack_alloc_ptr = NULL;
     }
 
diff --git a/arch/sh/src/common/up_usestack.c b/arch/sh/src/common/up_usestack.c
index ee26cb70c9b..1cc383a91db 100644
--- a/arch/sh/src/common/up_usestack.c
+++ b/arch/sh/src/common/up_usestack.c
@@ -89,7 +89,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 
   if (tcb->stack_alloc_ptr)
     {
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
     }
 
   /* Save the stack allocation */
diff --git a/arch/sim/src/up_createstack.c b/arch/sim/src/up_createstack.c
index fb7e8008112..a6ebcc5fa00 100644
--- a/arch/sim/src/up_createstack.c
+++ b/arch/sim/src/up_createstack.c
@@ -96,7 +96,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
 
   /* Allocate the memory for the stack */
 
-  uint32_t *stack_alloc_ptr = (uint32_t*)kmalloc(adj_stack_size);
+  uint32_t *stack_alloc_ptr = (uint32_t*)kumalloc(adj_stack_size);
   if (stack_alloc_ptr)
     {
       /* This is the address of the last word in the allocation */
diff --git a/arch/x86/src/i486/up_createstack.c b/arch/x86/src/i486/up_createstack.c
index 62a763b3094..927abcf2e23 100644
--- a/arch/x86/src/i486/up_createstack.c
+++ b/arch/x86/src/i486/up_createstack.c
@@ -93,7 +93,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
@@ -106,9 +106,9 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
        */
 
 #if defined(CONFIG_DEBUG) && !defined(CONFIG_DEBUG_STACK)
-      tcb->stack_alloc_ptr = (uint32_t *)kzalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kuzalloc(stack_size);
 #else
-      tcb->stack_alloc_ptr = (uint32_t *)kmalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kumalloc(stack_size);
 #endif
 #ifdef CONFIG_DEBUG
       if (!tcb->stack_alloc_ptr)
diff --git a/arch/x86/src/i486/up_releasestack.c b/arch/x86/src/i486/up_releasestack.c
index 47b3ea994dd..38a2dbfe81b 100644
--- a/arch/x86/src/i486/up_releasestack.c
+++ b/arch/x86/src/i486/up_releasestack.c
@@ -71,7 +71,7 @@ void up_release_stack(struct tcb_s *dtcb)
 {
   if (dtcb->stack_alloc_ptr)
     {
-      sched_free(dtcb->stack_alloc_ptr);
+      sched_ufree(dtcb->stack_alloc_ptr);
       dtcb->stack_alloc_ptr = NULL;
     }
 
diff --git a/arch/x86/src/i486/up_usestack.c b/arch/x86/src/i486/up_usestack.c
index 38290dd777f..8865a9e3fc1 100644
--- a/arch/x86/src/i486/up_usestack.c
+++ b/arch/x86/src/i486/up_usestack.c
@@ -88,7 +88,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 
   if (tcb->stack_alloc_ptr)
     {
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
     }
 
   /* Save the stack allocation */
diff --git a/arch/z16/src/common/up_createstack.c b/arch/z16/src/common/up_createstack.c
index b2deb4bf015..fcbf90bfec5 100644
--- a/arch/z16/src/common/up_createstack.c
+++ b/arch/z16/src/common/up_createstack.c
@@ -92,7 +92,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
@@ -105,9 +105,9 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
        */
 
 #if defined(CONFIG_DEBUG) && !defined(CONFIG_DEBUG_STACK)
-      tcb->stack_alloc_ptr = (uint32_t *)kzalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kuzalloc(stack_size);
 #else
-      tcb->stack_alloc_ptr = (uint32_t *)kmalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kumalloc(stack_size);
 #endif
 #ifdef CONFIG_DEBUG
       if (!tcb->stack_alloc_ptr)
diff --git a/arch/z16/src/common/up_releasestack.c b/arch/z16/src/common/up_releasestack.c
index 82ba1b122b5..f6618692588 100644
--- a/arch/z16/src/common/up_releasestack.c
+++ b/arch/z16/src/common/up_releasestack.c
@@ -71,7 +71,7 @@ void up_release_stack(struct tcb_s *dtcb)
 {
   if (dtcb->stack_alloc_ptr)
     {
-      sched_free(dtcb->stack_alloc_ptr);
+      sched_ufree(dtcb->stack_alloc_ptr);
       dtcb->stack_alloc_ptr = NULL;
     }
 
diff --git a/arch/z16/src/common/up_usestack.c b/arch/z16/src/common/up_usestack.c
index 9ebe01de4a3..671930bbeb7 100644
--- a/arch/z16/src/common/up_usestack.c
+++ b/arch/z16/src/common/up_usestack.c
@@ -89,7 +89,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 
   if (tcb->stack_alloc_ptr)
     {
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
     }
 
   /* Save the stack allocation */
diff --git a/arch/z80/src/common/up_createstack.c b/arch/z80/src/common/up_createstack.c
index c00f5f0715b..c086839bf20 100644
--- a/arch/z80/src/common/up_createstack.c
+++ b/arch/z80/src/common/up_createstack.c
@@ -91,7 +91,7 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
     {
       /* Yes.. free it */
 
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
       tcb->stack_alloc_ptr = NULL;
     }
 
@@ -104,9 +104,9 @@ int up_create_stack(struct tcb_s *tcb, size_t stack_size)
        */
 
 #if defined(CONFIG_DEBUG) && !defined(CONFIG_DEBUG_STACK)
-      tcb->stack_alloc_ptr = (uint32_t *)kzalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kuzalloc(stack_size);
 #else
-      tcb->stack_alloc_ptr = (uint32_t *)kmalloc(stack_size);
+      tcb->stack_alloc_ptr = (uint32_t *)kumalloc(stack_size);
 #endif
 #ifdef CONFIG_DEBUG
       if (!tcb->stack_alloc_ptr)
diff --git a/arch/z80/src/common/up_releasestack.c b/arch/z80/src/common/up_releasestack.c
index b5c9ef2f9da..346971610a7 100644
--- a/arch/z80/src/common/up_releasestack.c
+++ b/arch/z80/src/common/up_releasestack.c
@@ -71,7 +71,7 @@ void up_release_stack(struct tcb_s *dtcb)
 {
   if (dtcb->stack_alloc_ptr)
     {
-      sched_free(dtcb->stack_alloc_ptr);
+      sched_ufree(dtcb->stack_alloc_ptr);
       dtcb->stack_alloc_ptr = NULL;
     }
 
diff --git a/arch/z80/src/common/up_usestack.c b/arch/z80/src/common/up_usestack.c
index 0aaa5f906e3..f6fdb5fd46e 100644
--- a/arch/z80/src/common/up_usestack.c
+++ b/arch/z80/src/common/up_usestack.c
@@ -88,7 +88,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 
   if (tcb->stack_alloc_ptr)
     {
-      sched_free(tcb->stack_alloc_ptr);
+      sched_ufree(tcb->stack_alloc_ptr);
     }
 
   /* Save the stack allocation */