diff --git a/arch/x86_64/include/intel64/arch.h b/arch/x86_64/include/intel64/arch.h
index ebfb3e20f6..26d127d723 100644
--- a/arch/x86_64/include/intel64/arch.h
+++ b/arch/x86_64/include/intel64/arch.h
@@ -562,12 +562,12 @@ extern volatile uint8_t gdt64_low_end;
 
 /* The actual address of the page table and gdt/ist after mapping the kernel in high address*/
 
-volatile uint64_t *pdpt;
-volatile uint64_t *pd;
-volatile uint64_t *pt;
+extern volatile uint64_t *pdpt;
+extern volatile uint64_t *pd;
+extern volatile uint64_t *pt;
 
-volatile struct ist_s *ist64;
-volatile struct gdt_entry_s *gdt64;
+extern volatile struct ist_s *ist64;
+extern volatile struct gdt_entry_s *gdt64;
 
 /****************************************************************************
  * Public Function Prototypes
diff --git a/arch/x86_64/src/intel64/intel64_handlers.c b/arch/x86_64/src/intel64/intel64_handlers.c
index 6743ad222f..4dc1db7214 100644
--- a/arch/x86_64/src/intel64/intel64_handlers.c
+++ b/arch/x86_64/src/intel64/intel64_handlers.c
@@ -139,7 +139,6 @@ uint64_t *isr_handler(uint64_t *regs, uint64_t irq)
   PANIC(); /* Doesn't return */
   return regs;               /* To keep the compiler happy */
 #else
-  uint64_t *ret;
 
   DEBUGASSERT(g_current_regs == NULL);
   g_current_regs = regs;
diff --git a/arch/x86_64/src/intel64/intel64_lowsetup.c b/arch/x86_64/src/intel64/intel64_lowsetup.c
index ca9f07448a..ff63b81434 100644
--- a/arch/x86_64/src/intel64/intel64_lowsetup.c
+++ b/arch/x86_64/src/intel64/intel64_lowsetup.c
@@ -37,6 +37,19 @@
  * Private Data
  ****************************************************************************/
 
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/* The actual address of the page table and gdt/ist after mapping the kernel in high address*/
+
+volatile uint64_t *pdpt;
+volatile uint64_t *pd;
+volatile uint64_t *pt;
+
+volatile struct ist_s *ist64;
+volatile struct gdt_entry_s *gdt64;
+
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -64,16 +77,16 @@ void up_lowsetup(void)
 
   /* Setup pointers for accessing Page table and GDT in high address */
 
-  pdpt = &pdpt_low + X86_64_LOAD_OFFSET;
-  pd   = &pd_low   + X86_64_LOAD_OFFSET;
-  pt   = &pt_low   + X86_64_LOAD_OFFSET;
+  pdpt = (uint64_t *)((uintptr_t)&pdpt_low + X86_64_LOAD_OFFSET);
+  pd   = (uint64_t *)((uintptr_t)&pd_low   + X86_64_LOAD_OFFSET);
+  pt   = (uint64_t *)((uintptr_t)&pt_low   + X86_64_LOAD_OFFSET);
 
-  ist64     = (struct ist_s *)((void *)&ist64_low       + X86_64_LOAD_OFFSET);
-  gdt64     = (struct gdt_entry_s *)((void *)&gdt64_low + X86_64_LOAD_OFFSET);
+  ist64 = (struct ist_s *)((uintptr_t)&ist64_low       + X86_64_LOAD_OFFSET);
+  gdt64 = (struct gdt_entry_s *)((uintptr_t)&gdt64_low + X86_64_LOAD_OFFSET);
 
   /* reload the GDTR with mapped high memory address */
 
-  setgdt(gdt64, (uintptr_t)(&gdt64_low_end - &gdt64_low) - 1);
+  setgdt((void *)gdt64, (uintptr_t)(&gdt64_low_end - &gdt64_low) - 1);
 
   /* Do some checking on CPU compatibilities */
 
diff --git a/boards/x86_64/intel64/qemu-intel64/README.txt b/boards/x86_64/intel64/qemu-intel64/README.txt
index 46e44d1c4f..4f5b3b440f 100644
--- a/boards/x86_64/intel64/qemu-intel64/README.txt
+++ b/boards/x86_64/intel64/qemu-intel64/README.txt
@@ -42,7 +42,7 @@ set timeout=0
 set default=0
 menuentry "kernel" {
   multiboot2 /boot/nuttx.elf
-  }
+}
 ```
 
 ##### Making the disk
@@ -79,7 +79,7 @@ Running QEMU
 
   In the top-level NuttX directory:
 
-    qemu -cpu host -enable-kvm -m 2GB -cdrom boot.iso -nographic -serial mon:stdio
+    qemu-system-x86_64 -cpu host -enable-kvm -m 2G -cdrom boot.iso -nographic -serial mon:stdio
 
   This multiplex the qemu console and COM1 to your console.
   Use control-a 1 and 2 to switch between.