diff --git a/docs/content/main/configuration.md b/docs/content/main/configuration.md
index a9ad2fe..aefced7 100644
--- a/docs/content/main/configuration.md
+++ b/docs/content/main/configuration.md
@@ -118,11 +118,13 @@ Here you can include other config files so that they are merged together at star
 
 ```xml
 <includes>
-  <file path="./something.xml"/>
-  <file path="./somethingelse.xml"/>
+  <file path="./other_config_file.xml"/>
+  <file path="./other_config_file2.xml"/>
 </includes>
 ```
 
+If you define a variable/widget/window, in a config file, when it's defined somewhere else, you can see a warning in the eww logs (`eww logs`)
+
 ### The `<definitions>` block
 In here you whole widget will be made, and you can also create your own widgets. Check [Widget Documentation](@/main/widgets.md) for pre-defined widgets.
 
diff --git a/src/app.rs b/src/app.rs
index 4c930ba..7a0d8e5 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -265,7 +265,7 @@ impl App {
         // TODO somehow make this less shit
         for newly_used_var in self
             .variables_only_used_in(&window_name)
-            .filter_map(|var| self.eww_config.get_script_var(&var))
+            .filter_map(|var| self.eww_config.get_script_var(&var).ok())
         {
             self.script_var_handler.add(newly_used_var.clone());
         }
diff --git a/src/config/eww_config.rs b/src/config/eww_config.rs
index f11008e..ff0f0c2 100644
--- a/src/config/eww_config.rs
+++ b/src/config/eww_config.rs
@@ -14,24 +14,41 @@ use super::{
 use std::path::PathBuf;
 
 #[derive(Debug, Clone)]
+/// Structure to hold the eww config
 pub struct EwwConfig {
     widgets: HashMap<String, WidgetDefinition>,
     windows: HashMap<WindowName, EwwWindowDefinition>,
     initial_variables: HashMap<VarName, PrimitiveValue>,
-
-    // TODO make this a hashmap
-    script_vars: Vec<ScriptVar>,
+    script_vars: HashMap<VarName, ScriptVar>,
     pub filepath: PathBuf,
 }
 
 impl EwwConfig {
     pub fn merge_includes(mut eww_config: EwwConfig, includes: Vec<EwwConfig>) -> Result<EwwConfig> {
-        // TODO issue warnings on conflict
-        for config in includes {
-            eww_config.widgets.extend(config.widgets);
-            eww_config.windows.extend(config.windows);
-            eww_config.script_vars.extend(config.script_vars);
-            eww_config.initial_variables.extend(config.initial_variables);
+        let config_path = eww_config.filepath.clone();
+        let log_conflict = |what: &str, conflict: &str, included_path: &std::path::PathBuf| {
+            eprintln!(
+                "{} '{}' defined twice (defined in {} and in {})",
+                what,
+                conflict,
+                config_path.display(),
+                included_path.display()
+            );
+        };
+
+        for included_config in includes {
+            for conflict in extend_safe(&mut eww_config.widgets, included_config.widgets) {
+                log_conflict("widget", &conflict, &included_config.filepath)
+            }
+            for conflict in extend_safe(&mut eww_config.windows, included_config.windows) {
+                log_conflict("window", &conflict.to_string(), &included_config.filepath)
+            }
+            for conflict in extend_safe(&mut eww_config.script_vars, included_config.script_vars) {
+                log_conflict("script-var", &conflict.to_string(), &included_config.filepath)
+            }
+            for conflict in extend_safe(&mut eww_config.initial_variables, included_config.initial_variables) {
+                log_conflict("var", &conflict.to_string(), &included_config.filepath)
+            }
         }
         Ok(eww_config)
     }
@@ -118,7 +135,7 @@ impl EwwConfig {
         let mut vars = self
             .script_vars
             .iter()
-            .map(|var| Ok((var.name().clone(), var.initial_value()?)))
+            .map(|var| Ok((var.0.clone(), var.1.initial_value()?)))
             .collect::<Result<HashMap<_, _>>>()?;
         vars.extend(self.get_default_vars().clone());
         Ok(vars)
@@ -142,18 +159,20 @@ impl EwwConfig {
         &self.initial_variables
     }
 
-    pub fn get_script_vars(&self) -> &Vec<ScriptVar> {
-        &self.script_vars
+    pub fn get_script_vars(&self) -> Vec<ScriptVar> {
+        self.script_vars.values().cloned().collect()
     }
 
-    pub fn get_script_var(&self, name: &VarName) -> Option<&ScriptVar> {
-        self.script_vars.iter().find(|x| x.name() == name)
+    pub fn get_script_var(&self, name: &VarName) -> Result<&ScriptVar> {
+        self.script_vars
+            .get(name)
+            .with_context(|| format!("No script var named '{}' exists", name))
     }
 }
 
-fn parse_variables_block(xml: XmlElement) -> Result<(HashMap<VarName, PrimitiveValue>, Vec<ScriptVar>)> {
+fn parse_variables_block(xml: XmlElement) -> Result<(HashMap<VarName, PrimitiveValue>, HashMap<VarName, ScriptVar>)> {
     let mut normal_vars = HashMap::new();
-    let mut script_vars = Vec::new();
+    let mut script_vars = HashMap::new();
     for node in xml.child_elements() {
         match node.tag_name() {
             "var" => {
@@ -165,7 +184,8 @@ fn parse_variables_block(xml: XmlElement) -> Result<(HashMap<VarName, PrimitiveV
                 normal_vars.insert(var_name, PrimitiveValue::from_string(value));
             }
             "script-var" => {
-                script_vars.push(ScriptVar::from_xml_element(node)?);
+                let script_var = ScriptVar::from_xml_element(node)?;
+                script_vars.insert(script_var.name().clone(), script_var);
             }
             _ => bail!("Illegal element in variables block: {}", node.as_tag_string()),
         }
@@ -187,6 +207,16 @@ fn join_path_pretty<P: AsRef<std::path::Path>, P2: AsRef<std::path::Path>>(a: P,
     }
 }
 
+/// extends a hashmap, returning a list of keys that already where present in the hashmap.
+fn extend_safe<K: std::cmp::Eq + std::hash::Hash + Clone, V, T: IntoIterator<Item = (K, V)>>(
+    a: &mut HashMap<K, V>,
+    b: T,
+) -> Vec<K> {
+    b.into_iter()
+        .filter_map(|(k, v)| a.insert(k.clone(), v).map(|_| k.clone()))
+        .collect()
+}
+
 #[cfg(test)]
 mod test {
     use crate::config::{EwwConfig, XmlNode};
@@ -254,7 +284,7 @@ mod test {
             widgets: HashMap::new(),
             windows: HashMap::new(),
             initial_variables: HashMap::new(),
-            script_vars: Vec::new(),
+            script_vars: HashMap::new(),
             filepath: "test_path".into(),
         };
 
diff --git a/src/main.rs b/src/main.rs
index 9d4fa46..51fbb95 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -90,7 +90,7 @@ fn main() {
                 } else {
                     log::info!("Initializing Eww server.");
                     let _ = std::fs::remove_file(&*crate::IPC_SOCKET_PATH);
-                    println!("Run `eww logs` to see any errors, warnings or informatiion while editing your configuration.");
+                    println!("Run `eww logs` to see any errors, warnings or information while editing your configuration.");
                     server::initialize_server()?;
                 }
             }