diff --git a/user/src/bin/forktest2.rs b/user/src/bin/forktest2.rs
index 493fccd8..d08a4120 100644
--- a/user/src/bin/forktest2.rs
+++ b/user/src/bin/forktest2.rs
@@ -22,12 +22,12 @@ pub fn main() -> i32 {
         }
     }
 
-    let mut xstate: i32 = 0;
+    let mut exit_code: i32 = 0;
     for _ in 0..NUM {
-        assert!(wait(&mut xstate) > 0);
-        assert_eq!(xstate, 0);
+        assert!(wait(&mut exit_code) > 0);
+        assert_eq!(exit_code, 0);
     }
-    assert!(wait(&mut xstate) < 0);
+    assert!(wait(&mut exit_code) < 0);
     println!("forktest2 test passed!");
     0
 }
\ No newline at end of file
diff --git a/user/src/bin/forktest_simple.rs b/user/src/bin/forktest_simple.rs
index 1851aea0..821fba64 100644
--- a/user/src/bin/forktest_simple.rs
+++ b/user/src/bin/forktest_simple.rs
@@ -18,11 +18,11 @@ pub fn main() -> i32 {
         100
     } else {
         // parent process
-        let mut xstate: i32 = 0;
+        let mut exit_code: i32 = 0;
         println!("ready waiting on parent process!");
-        assert_eq!(pid, wait(&mut xstate));
-        assert_eq!(xstate, 100);
-        println!("child process pid = {}, exit code = {}", pid, xstate);
+        assert_eq!(pid, wait(&mut exit_code));
+        assert_eq!(exit_code, 100);
+        println!("child process pid = {}, exit code = {}", pid, exit_code);
         0
     }
 }
\ No newline at end of file
diff --git a/user/src/bin/matrix.rs b/user/src/bin/matrix.rs
index 95904337..8ef2c044 100644
--- a/user/src/bin/matrix.rs
+++ b/user/src/bin/matrix.rs
@@ -56,13 +56,13 @@ pub fn main() -> i32 {
 
     println!("fork ok.");
 
-    let mut xstate: i32 = 0;
+    let mut exit_code: i32 = 0;
     for _ in 0..NUM {
-        if wait(&mut xstate) < 0 {
+        if wait(&mut exit_code) < 0 {
             panic!("wait failed.");
         }
     }
-    assert!(wait(&mut xstate) < 0);
+    assert!(wait(&mut exit_code) < 0);
     println!("matrix passed.");
     0
 }
\ No newline at end of file
diff --git a/user/src/bin/sleep.rs b/user/src/bin/sleep.rs
index d05d6248..bd1e2204 100644
--- a/user/src/bin/sleep.rs
+++ b/user/src/bin/sleep.rs
@@ -19,11 +19,11 @@ fn sleepy() {
 pub fn main() -> i32 {
     let current_time = get_time();
     let pid = fork();
-    let mut xstate: i32 = 0;
+    let mut exit_code: i32 = 0;
     if pid == 0 {
         sleepy();
     }
-    assert!(waitpid(pid as usize, &mut xstate) == pid && xstate == 0);
+    assert!(waitpid(pid as usize, &mut exit_code) == pid && exit_code == 0);
     println!("use {} msecs.", get_time() - current_time);
     println!("sleep pass.");
     0
diff --git a/user/src/bin/usertests.rs b/user/src/bin/usertests.rs
index d5d0d7d2..7a4a6d7b 100644
--- a/user/src/bin/usertests.rs
+++ b/user/src/bin/usertests.rs
@@ -29,10 +29,10 @@ pub fn main() -> i32 {
             exec(*test);
             panic!("unreachable!");
         } else {
-            let mut xstate: i32 = Default::default();
-            let wait_pid = waitpid(pid as usize, &mut xstate);
+            let mut exit_code: i32 = Default::default();
+            let wait_pid = waitpid(pid as usize, &mut exit_code);
             assert_eq!(pid, wait_pid);
-            println!("\x1b[32mUsertests: Test {} in Process {} exited with code {}\x1b[0m", test, pid, xstate);
+            println!("\x1b[32mUsertests: Test {} in Process {} exited with code {}\x1b[0m", test, pid, exit_code);
         }
     }
     println!("Usertests passed!");