diff --git a/src/erg_common/python_util.rs b/src/erg_common/python_util.rs
index d3b62283..2dd8f7fd 100644
--- a/src/erg_common/python_util.rs
+++ b/src/erg_common/python_util.rs
@@ -11,10 +11,14 @@ pub fn which_python() -> String {
         .arg(python)
         .output()
         .expect("python not found");
-    String::from_utf8(out.stdout)
+    let res = String::from_utf8(out.stdout)
         .unwrap()
         .replace("\n", "")
-        .replace("\r", "")
+        .replace("\r", "");
+    if res == "" {
+        panic!("python not found");
+    }
+    res
 }
 
 pub fn detect_magic_number() -> u32 {
@@ -28,7 +32,6 @@ pub fn detect_magic_number() -> u32 {
         .output()
         .expect("cannot get the magic number from python");
     let s_hex_magic_num = String::from_utf8(out.stdout).unwrap();
-    dbg!(&s_hex_magic_num);
     let first_byte = u8::from_str_radix(&s_hex_magic_num[0..=1], 16).unwrap();
     let second_byte = u8::from_str_radix(&s_hex_magic_num[2..=3], 16).unwrap();
     get_magic_num_from_bytes(&[first_byte, second_byte, 0, 0])