diff --git a/proc.c b/proc.c
index 751d886..9e95529 100644
--- a/proc.c
+++ b/proc.c
@@ -302,7 +302,12 @@ scheduler(void)
 }
 
 // Enter scheduler.  Must hold only ptable.lock
-// and have changed proc->state.
+// and have changed proc->state. Saves and restores
+// intena because intena is a property of this
+// kernel thread, not this CPU. It should
+// be proc->intena and proc->ncli, but that would
+// break in the few places where a lock is held but
+// there's no process.
 void
 sched(void)
 {
diff --git a/spinlock.c b/spinlock.c
index a5f0b21..bf863ef 100644
--- a/spinlock.c
+++ b/spinlock.c
@@ -102,8 +102,9 @@ pushcli(void)
 
   eflags = readeflags();
   cli();
-  if(cpu->ncli++ == 0)
+  if(cpu->ncli == 0)
     cpu->intena = eflags & FL_IF;
+  cpu->ncli += 1;
 }
 
 void
diff --git a/vm.c b/vm.c
index c8b8d35..d9aaa7e 100644
--- a/vm.c
+++ b/vm.c
@@ -27,7 +27,7 @@ seginit(void)
   c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, DPL_USER);
   c->gdt[SEG_UDATA] = SEG(STA_W, 0, 0xffffffff, DPL_USER);
 
-  // Map cpu and curproc -- these are private per cpu.
+  // Map cpu and proc -- these are private per cpu.
   c->gdt[SEG_KCPU] = SEG(STA_W, &c->cpu, 8, 0);
 
   lgdt(c->gdt, sizeof(c->gdt));