diff --git a/chsrc.c b/chsrc.c
index e192138..91a8d86 100644
--- a/chsrc.c
+++ b/chsrc.c
@@ -846,6 +846,8 @@ os_ubuntu_getsrc(char* option)
 void
 os_ubuntu_setsrc (char* option)
 {
+  ensure_root();
+
   int index = 0;
 
   if (NULL!=option) {
@@ -879,8 +881,7 @@ os_ubuntu_setsrc (char* option)
       "-ports/@\'< /etc/apt/sources.list.bak | cat > /etc/apt/sources.list");
   }
 
-  chsrc_logcmd(cmd);
-  system(cmd);
+  chsrc_runcmd(cmd);
   // char* rm = "rm -rf /etc/apt/source.list.bak";
   // system(rm);
 
diff --git a/chsrc.h b/chsrc.h
index fade0b0..795ecec 100644
--- a/chsrc.h
+++ b/chsrc.h
@@ -261,6 +261,29 @@ chsrc_say_thanks (source_info* source)
 }
 
 
+
+void
+ensure_root ()
+{
+  char* euid = getenv("$EUID");
+  if (NULL==euid) {
+    FILE* fp = popen("id -u", "r");
+    char buf[10] = {0};
+    fgets(buf, 10, fp);
+    fclose(fp);
+    if (0!=atoi(buf)) goto not_root;
+    else return;
+  } else {
+    if (0!=atoi(euid)) goto not_root;
+    else return;
+  }
+not_root:
+  xy_error("chsrc: 请在命令前使用 sudo 来保证必要的权限");
+  exit(1);
+}
+
+
+
 /* Target Info */
 typedef struct {
   void (*setfn)(char* option);