diff --git a/libconfig/src/lib.rs b/libconfig/src/lib.rs
index 8075bdc..aeabcbe 100644
--- a/libconfig/src/lib.rs
+++ b/libconfig/src/lib.rs
@@ -230,8 +230,8 @@ impl Config {
         Ok(())
     }
     pub fn write_str<'b>(&mut self, key: &str, data: &str) -> Result<'b, ()>{
-        let call_remove_config_key_bin = false;
-        let call_remove_config_txt = false;
+        let mut call_remove_config_key_bin = false;
+        let mut call_remove_config_txt = false;
 
         if let Some(fs) = &self.fs {
             let root_dir = fs.root_dir();