diff --git a/Cargo.lock b/Cargo.lock
index a54f055..ed86b11 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3873,6 +3873,7 @@ dependencies = [
  "serde",
  "serde_default",
  "serde_json",
+ "tempfile",
  "tokio",
  "toml 0.7.5",
  "wayland-backend",
diff --git a/src/config.rs b/src/config.rs
index 829f6e8..80cdb14 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -111,13 +111,9 @@ pub fn from_cli() -> anyhow::Result<RunnerConfig> {
 pub fn new_with_cli(matches: &ArgMatches) -> anyhow::Result<FileConfig> {
     let mut config_path = None;
     if matches.contains_id("config") {
-        let config_file = matches.get_one::<String>("config");
+        let config_file = matches.get_one::<PathBuf>("config");
         if let Some(path) = config_file {
-            if let Err(e) = std::fs::metadata(path) {
-                warn!("Invalid config filename, using the default config: {e}");
-            } else {
-                config_path = Some(Path::new(path).to_path_buf());
-            }
+            config_path = Some(Path::new(path).to_path_buf());
         }
     }
     let mut config = FileConfig::new(config_path)?;
diff --git a/watchers/Cargo.toml b/watchers/Cargo.toml
index de8c254..9714bef 100644
--- a/watchers/Cargo.toml
+++ b/watchers/Cargo.toml
@@ -11,6 +11,7 @@ path = "src/lib.rs"
 
 [dev-dependencies]
 rstest = "0.17.0"
+tempfile = "3.5.0"
 
 [dependencies]
 aw-client-rust = { git = "https://github.com/2e3s/aw-server-rust", rev = "81db4c8" }
diff --git a/watchers/src/config/file_config.rs b/watchers/src/config/file_config.rs
index dc4dea3..4b4fa79 100644
--- a/watchers/src/config/file_config.rs
+++ b/watchers/src/config/file_config.rs
@@ -1,7 +1,7 @@
 use anyhow::{anyhow, Context};
 use serde::Deserialize;
 use serde_default::DefaultFromSerde;
-use std::{io::ErrorKind, path::PathBuf, time::Duration};
+use std::{fs, io::ErrorKind, path::PathBuf, time::Duration};
 
 use crate::config::defaults;
 
@@ -97,8 +97,15 @@ pub struct FileConfig {
 
 impl FileConfig {
     pub fn new(config_override: Option<PathBuf>) -> anyhow::Result<Self> {
+        let is_config_overridden = config_override.is_some();
         let config_path = if let Some(config_override) = config_override {
-            config_override
+            if config_override.starts_with("~/") {
+                dirs::home_dir()
+                    .ok_or(anyhow!("Home directory is not found"))?
+                    .join(config_override.strip_prefix("~").unwrap())
+            } else {
+                config_override
+            }
         } else {
             let mut system_config_path: PathBuf =
                 dirs::config_dir().ok_or(anyhow!("Config directory is unknown"))?;
@@ -108,7 +115,7 @@ impl FileConfig {
             system_config_path
         };
 
-        let mut config = if config_path.exists() {
+        let mut config = if fs::metadata(&config_path).is_ok() {
             debug!("Reading config at {}", config_path.display());
             let config_content = std::fs::read_to_string(&config_path).with_context(|| {
                 format!("Impossible to read config file {}", config_path.display())
@@ -116,6 +123,9 @@ impl FileConfig {
 
             toml::from_str(&config_content)?
         } else {
+            if is_config_overridden {
+                anyhow::bail!("Config file is not accessible at {}", config_path.display());
+            }
             let config = default_config();
             let error = std::fs::create_dir(config_path.parent().unwrap());
             if let Err(e) = error {
@@ -133,3 +143,102 @@ impl FileConfig {
         Ok(config)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use rstest::rstest;
+    use std::io::Write;
+    use tempfile::NamedTempFile;
+
+    #[rstest]
+    fn all() {
+        let mut file = NamedTempFile::new().unwrap();
+        write!(
+            file,
+            r#"
+[server]
+port = 1234
+host = "http://address.com"
+
+[awatcher]
+idle-timeout-seconds=14
+poll-time-idle-seconds=13
+poll-time-window-seconds=12
+
+# Add as many filters as needed.
+# There should be at least 1 match field, and at least 1 replace field.
+[[awatcher.filters]]
+match-app-id = "firefox"
+replace-title = "Unknown"
+
+[[awatcher.filters]]
+match-app-id = "code"
+match-title = "title"
+replace-app-id = "VSCode"
+replace-title = "Title"
+        "#
+        )
+        .unwrap();
+
+        let config = FileConfig::new(Some(file.path().to_path_buf())).unwrap();
+
+        assert_eq!(1234, config.server.port);
+        assert_eq!("http://address.com", config.server.host);
+
+        assert_eq!(14, config.client.idle_timeout_seconds);
+        assert_eq!(13, config.client.poll_time_idle_seconds);
+        assert_eq!(12, config.client.poll_time_window_seconds);
+
+        assert_eq!(2, config.client.filters.len());
+        let replacement1 = config.client.filters[0]
+            .replacement("firefox", "any")
+            .unwrap();
+        assert_eq!(None, replacement1.replace_app_id);
+        assert_eq!(Some("Unknown".to_string()), replacement1.replace_title);
+        let replacement2 = config.client.filters[1]
+            .replacement("code", "title")
+            .unwrap();
+        assert_eq!(Some("VSCode".to_string()), replacement2.replace_app_id);
+        assert_eq!(Some("Title".to_string()), replacement2.replace_title);
+    }
+
+    #[rstest]
+    fn empty() {
+        let mut file = NamedTempFile::new().unwrap();
+        write!(file, "[awatcher]").unwrap();
+
+        let config = FileConfig::new(Some(file.path().to_path_buf())).unwrap();
+
+        assert_eq!(defaults::port(), config.server.port);
+        assert_eq!(defaults::host(), config.server.host);
+
+        assert_eq!(
+            defaults::idle_timeout_seconds(),
+            config.client.idle_timeout_seconds
+        );
+        assert_eq!(
+            defaults::poll_time_idle_seconds(),
+            config.client.poll_time_idle_seconds
+        );
+        assert_eq!(
+            defaults::poll_time_window_seconds(),
+            config.client.poll_time_window_seconds
+        );
+
+        assert_eq!(0, config.client.filters.len());
+    }
+
+    #[rstest]
+    fn wrong_file() {
+        let file = PathBuf::new();
+
+        let config = FileConfig::new(Some(file));
+
+        assert!(config.is_err());
+        assert_eq!(
+            "Config file is not accessible at ",
+            config.err().unwrap().to_string()
+        );
+    }
+}