diff --git a/src/headers/SemanticAnalysis.hpp b/src/headers/SemanticAnalysis.hpp
index c126fd6..d1feadb 100644
--- a/src/headers/SemanticAnalysis.hpp
+++ b/src/headers/SemanticAnalysis.hpp
@@ -21,18 +21,28 @@ struct SemanticAnalyser final: public Tasking {
         return tree;
     }
 private:
-    unordered_task_map getTaskMapInstance() final { // TODO Include line in error messages
+    unordered_task_map getTaskMapInstance() final {
         using namespace StandardComponents;
         return {
             make_nonlocal_task(Function,
-                if (index > 0 and any_of(parsedTree.cbegin(), parsedTree.cbegin() + index + 1, [&parseComponent](const component_ptr& pointer){
+                if (index > 0 and any_of(parsedTree.cbegin(), parsedTree.cbegin() + index, [&parseComponent](const component_ptr& pointer){
                     if (pointer->getId() != typeid(Reference)) {
+                        string_view ptr_name;
                         try {
-                            return dynamic_cast<NamedIdentifier<true>&>(*pointer).name == parseComponent.name;
-                        } catch (const bad_cast&) {};
+                            ptr_name = dynamic_cast<NamedIdentifier<true>&>(*pointer).name;
+                        } catch (const bad_cast&) {
+                            try {
+                                ptr_name = dynamic_cast<NamedIdentifier<false>&>(*pointer).name;
+                            } catch (const bad_cast&) {
+                                return false;
+                            }
+                        };
+                        if (ptr_name == parseComponent.name) {
+                            return true;
+                        }
                     }
                     return false;
-                })) { error(parseComponent.name + " has already been defined previously"); }
+                })) { error(parseComponent.name + " has already been defined previously", parseComponent.line); }
             ),
             share_task(Function, Class),
             share_task(Function, Define<true>),
diff --git a/src/headers/parsing/ParseComponents.hpp b/src/headers/parsing/ParseComponents.hpp
index eaa07d3..0484f10 100644
--- a/src/headers/parsing/ParseComponents.hpp
+++ b/src/headers/parsing/ParseComponents.hpp
@@ -24,6 +24,7 @@ template<bool disallow_reserved>
 struct NamedIdentifier: virtual ParseComponent {
     struct identifier_reserved_exception: exception {};
     const string name;
+    unsigned long line = 0;
     explicit NamedIdentifier(const string_view nameText): name(nameText) {
         if (disallow_reserved and reserved(name)) {
             throw identifier_reserved_exception();
diff --git a/src/headers/parsing/Parser.hpp b/src/headers/parsing/Parser.hpp
index 6974403..a2be489 100644
--- a/src/headers/parsing/Parser.hpp
+++ b/src/headers/parsing/Parser.hpp
@@ -184,6 +184,16 @@ namespace Parser {
             } catch (const NamedIdentifier<true>::identifier_reserved_exception&) {
                 parsingError(current, " is a reserved identifier", true);
             }
+            if (!parseTree.empty()) {
+                const component_ptr& last = parseTree[parseTree.size() - 1];
+                try {
+                    dynamic_cast<NamedIdentifier<true>&>(*last).line = current.line;
+                } catch (const bad_cast&) {
+                    try {
+                        dynamic_cast<NamedIdentifier<false>&>(*last).line = current.line;
+                    } catch (const bad_cast&) {}
+                }
+            }
         }
         return parseTree;
     }