diff --git a/bin/src/addons.rs b/bin/src/addons.rs
index d8962bf6..f89b7e3e 100644
--- a/bin/src/addons.rs
+++ b/bin/src/addons.rs
@@ -101,6 +101,25 @@ impl Addon {
         for location in [Location::Addons, Location::Optionals] {
             addons.extend(location.scan()?);
         }
+        for addon in &addons {
+            if addon.name().to_lowercase() != addon.name() {
+                warn!(
+                    "Addon name {} is not lowercase, it is highly recommended to use lowercase names",
+                    addon.name()
+                );
+            }
+            if addons.iter().any(|a| {
+                a.name().to_lowercase() == addon.name().to_lowercase() && a.name() != addon.name()
+            }) {
+                return Err(Error::AddonNameDuplicate(addon.name().to_string()));
+            }
+            if addons.iter().any(|a| {
+                a.name().to_lowercase() == addon.name().to_lowercase()
+                    && a.location() != addon.location()
+            }) {
+                return Err(Error::AddonDuplicate(addon.name().to_string()));
+            }
+        }
         Ok(addons)
     }
 }
diff --git a/bin/src/commands/build.rs b/bin/src/commands/build.rs
index bec197bd..78decb4a 100644
--- a/bin/src/commands/build.rs
+++ b/bin/src/commands/build.rs
@@ -52,7 +52,7 @@ pub fn pre_execute(matches: &ArgMatches) -> Result<(), Error> {
     let just = matches
         .get_many::<String>("just")
         .unwrap_or_default()
-        .map(std::string::String::as_str)
+        .map(|s| s.to_lowercase())
         .collect::<Vec<_>>();
     let mut ctx = Context::new(
         std::env::current_dir()?,
@@ -65,7 +65,7 @@ pub fn pre_execute(matches: &ArgMatches) -> Result<(), Error> {
         },
     )?;
     if !just.is_empty() {
-        ctx = ctx.filter(|a, _| just.contains(&a.name()));
+        ctx = ctx.filter(|a, _| just.contains(&a.name().to_lowercase()));
     }
     let mut executor = Executor::new(&ctx);
 
diff --git a/bin/src/commands/dev.rs b/bin/src/commands/dev.rs
index 3daf8a6d..b5f498eb 100644
--- a/bin/src/commands/dev.rs
+++ b/bin/src/commands/dev.rs
@@ -59,7 +59,7 @@ pub fn execute(matches: &ArgMatches, launch_optionals: &[String]) -> Result<Cont
     let just = matches
         .get_many::<String>("just")
         .unwrap_or_default()
-        .map(std::string::String::as_str)
+        .map(|s| s.to_lowercase())
         .collect::<Vec<_>>();
 
     let ctx = Context::new(
@@ -73,7 +73,7 @@ pub fn execute(matches: &ArgMatches, launch_optionals: &[String]) -> Result<Cont
         },
     )?
     .filter(|a, config| {
-        if !just.is_empty() && !just.contains(&a.name()) {
+        if !just.is_empty() && !just.contains(&a.name().to_lowercase()) {
             return false;
         }
         if launch_optionals.iter().any(|o| o == a.name()) {
diff --git a/bin/src/error.rs b/bin/src/error.rs
index 3d17f5a4..704d8ccb 100644
--- a/bin/src/error.rs
+++ b/bin/src/error.rs
@@ -16,6 +16,10 @@ pub enum Error {
     #[error("New can only be ran in an interactive terminal")]
     NewNoInput,
 
+    #[error("Addon duplicated with different case: {0}")]
+    AddonNameDuplicate(String),
+    #[error("Addon present in addons and optionals: {0}")]
+    AddonDuplicate(String),
     #[error("Invalid addon location: {0}")]
     AddonLocationInvalid(String),
     #[error("Optional addon not found: {0}")]