diff --git a/crates/aiken-lang/src/ast.rs b/crates/aiken-lang/src/ast.rs
index ace86680..b9447de8 100644
--- a/crates/aiken-lang/src/ast.rs
+++ b/crates/aiken-lang/src/ast.rs
@@ -81,10 +81,10 @@ impl TypedModule {
     pub fn has_definition(&self, name: &str) -> bool {
         self.definitions.iter().any(|def| match def {
             Definition::Fn(f) => f.public && f.name == name,
-            Definition::TypeAlias(_) => false,
-            Definition::DataType(_) => false,
+            Definition::TypeAlias(alias) => alias.public && alias.alias == name,
+            Definition::ModuleConstant(cst) => cst.public && cst.name == name,
+            Definition::DataType(t) => t.public && t.name == name,
             Definition::Use(_) => false,
-            Definition::ModuleConstant(_) => false,
             Definition::Test(_) => false,
             Definition::Validator(_) => false,
         })
diff --git a/crates/aiken-lang/src/tipo/error.rs b/crates/aiken-lang/src/tipo/error.rs
index 3fcdb18b..93706a8c 100644
--- a/crates/aiken-lang/src/tipo/error.rs
+++ b/crates/aiken-lang/src/tipo/error.rs
@@ -968,15 +968,15 @@ impl ExtraData for Error {
             | Error::UnknownModuleType { .. }
             | Error::UnknownModuleValue { .. }
             | Error::UnknownRecordField { .. }
-            | Error::UnknownType { .. }
-            | Error::UnknownTypeConstructor { .. }
             | Error::UnnecessarySpreadOperator { .. }
             | Error::UpdateMultiConstructorType { .. }
             | Error::ValidatorImported { .. }
             | Error::ValidatorMustReturnBool { .. } => None,
-            Error::UnknownVariable { name, .. } | Error::UnknownModule { name, .. } => {
-                Some(name.clone())
-            }
+
+            Error::UnknownType { name, .. }
+            | Error::UnknownTypeConstructor { name, .. }
+            | Error::UnknownVariable { name, .. }
+            | Error::UnknownModule { name, .. } => Some(name.clone()),
         }
     }
 }
diff --git a/crates/aiken-lsp/src/quickfix.rs b/crates/aiken-lsp/src/quickfix.rs
index ca745991..f21eb48b 100644
--- a/crates/aiken-lsp/src/quickfix.rs
+++ b/crates/aiken-lsp/src/quickfix.rs
@@ -5,8 +5,8 @@ use crate::{
 use std::collections::HashMap;
 
 const UNKNOWN_VARIABLE: &str = "aiken::check::unknown::variable";
-
 const UNKNOWN_MODULE: &str = "aiken::check::unknown::module";
+const UNKNOWN_TYPE: &str = "aiken::check::unknown::type";
 
 /// Errors for which we can provide quickfixes
 pub enum Quickfix {
@@ -23,11 +23,19 @@ fn match_code(diagnostic: &lsp_types::Diagnostic, expected: &str) -> bool {
 pub fn assert(diagnostic: &lsp_types::Diagnostic) -> Option<Quickfix> {
     let is_error = diagnostic.severity == Some(lsp_types::DiagnosticSeverity::ERROR);
 
-    if is_error && match_code(diagnostic, UNKNOWN_VARIABLE) {
+    if !is_error {
+        return None;
+    }
+
+    if match_code(diagnostic, UNKNOWN_VARIABLE) {
         return Some(Quickfix::UnknownIdentifier);
     }
 
-    if is_error && match_code(diagnostic, UNKNOWN_MODULE) {
+    if match_code(diagnostic, UNKNOWN_TYPE) {
+        return Some(Quickfix::UnknownIdentifier);
+    }
+
+    if match_code(diagnostic, UNKNOWN_MODULE) {
         return Some(Quickfix::UnknownModule);
     }