diff --git a/console.c b/console.c
index 5dad05a..75dd82e 100644
--- a/console.c
+++ b/console.c
@@ -53,7 +53,7 @@ real_cons_putc(int c)
   } else {
     c |= 0x0700; // black on white
     crt[ind] = c;
-    ind += 1;
+    ind++;
   }
 
   if((ind / 80) >= 24){
@@ -100,10 +100,8 @@ printint(int xx, int base, int sgn)
   if(neg)
     buf[i++] = '-';
 
-  while(i > 0){
-    i -= 1;
+  while(--i >= 0)
     real_cons_putc(buf[i]);
-  }
 }
 
 /*
diff --git a/fd.c b/fd.c
index b34f313..68f75e3 100644
--- a/fd.c
+++ b/fd.c
@@ -104,6 +104,6 @@ fd_incref(struct fd *fd)
   acquire(&fd_table_lock);
   if(fd->count < 1 || fd->type == FD_CLOSED)
     panic("fd_reference");
-  fd->count += 1;
+  fd->count++;
   release(&fd_table_lock);
 }
diff --git a/trap.c b/trap.c
index b210541..78a62f0 100644
--- a/trap.c
+++ b/trap.c
@@ -71,13 +71,8 @@ trap(struct Trapframe *tf)
     if(cpus[cpu()].nlock)
       panic("timer interrupt while holding a lock");
     if(cp){
-#if 1
       if((read_eflags() & FL_IF) == 0)
         panic("timer interrupt but interrupts now disabled");
-#else
-      cpus[cpu()].clis += 1;
-      sti();
-#endif
       if(cp->killed)
         proc_exit();
       if(cp->state == RUNNING)