diff --git a/debug.h b/debug.h
index 0aeed2f..4dec59a 100644
--- a/debug.h
+++ b/debug.h
@@ -20,6 +20,16 @@
 #include <stdio.h>
 #include <assert.h>
 
+#ifdef __DEBUG_LEVEL__
+#undef __DEBUG_LEVEL__
+#endif
+/* You can change the debug level here
+ * 0: no log
+ * 1: Assert
+ * 2: Assert + Log
+ */ 
+#define __DEBUG_LEVEL__ 9
+
 // ----------- log -----------
 
 #define ANSI_FG_BLACK   "\33[1;30m"
@@ -52,10 +62,15 @@
     printf(__VA_ARGS__); \
   } while (0)
 
+#if __DEBUG_LEVEL__ >= 2
 #define Log(format, ...) \
     _Log(ANSI_FMT("[%s:%d %s] " format, ANSI_FG_BLUE) "\n", \
         __FILE__, __LINE__, __func__, ## __VA_ARGS__)
+#else
+#define Log(format, ...) (NULL)
+#endif
 
+#ifdef __DEBUG_LEVEL__ >= 1
 #define Assert(cond, format, ...) \
   do { \
     if (!(cond)) { \
@@ -64,6 +79,9 @@
         assert(cond); \
     } \
   } while (0)
+#else
+#define Assert(cond, format, ...) (NULL)
+#endif
 
 #define panic(format, ...) Assert(0, format, ## __VA_ARGS__)
 
diff --git a/main.c b/main.c
index dacd6fe..0b8df29 100644
--- a/main.c
+++ b/main.c
@@ -45,7 +45,7 @@ static struct {
 } cmd_table [] = {
     { "help", "Display information about all supported commands", cmd_help },
     { "p", "p EXPR: To evaluate an expression EXPR and output the result", cmd_p },
-    { "q", "Exit NEMU", cmd_q },
+    { "q", "Exit EXPR", cmd_q },
 
     /* TODO: Add more commands */