diff --git a/src/Diagnostics/Diagnostic.hpp b/src/Diagnostics/Diagnostic.hpp
index 3d6a23c..88ee57e 100644
--- a/src/Diagnostics/Diagnostic.hpp
+++ b/src/Diagnostics/Diagnostic.hpp
@@ -16,6 +16,7 @@ namespace Porygon::Diagnostics {
         unsigned int _start;
         unsigned int _length;
         std::vector<std::string> _arguments;
+        std::string* _message;
     public:
         Diagnostic(DiagnosticSeverity severity, DiagnosticCode code, unsigned int start, unsigned int length, std::vector<std::string> arguments) {
             _severity = severity;
@@ -23,6 +24,11 @@ namespace Porygon::Diagnostics {
             _start = start;
             _length = length;
             _arguments = std::move(arguments);
+            _message = nullptr;
+        }
+
+        ~Diagnostic(){
+            delete _message;
         }
 
         DiagnosticSeverity GetSeverity() {
@@ -44,6 +50,14 @@ namespace Porygon::Diagnostics {
         std::vector<std::string> GetArguments(){
             return _arguments;
         }
+
+        void SetMessage(std::string* s){
+            this -> _message = s;
+        }
+
+        std::string* GetMessage(){
+            return _message;
+        }
     };
 }
 #endif //PORYGONLANG_DIAGNOSTIC_HPP
diff --git a/src/Diagnostics/DiagnosticsHolder.cpp b/src/Diagnostics/DiagnosticsHolder.cpp
index 3891b19..bf5603c 100644
--- a/src/Diagnostics/DiagnosticsHolder.cpp
+++ b/src/Diagnostics/DiagnosticsHolder.cpp
@@ -97,7 +97,11 @@ const string PrettyDiagnostic ( const char * format, vector<string> arguments)
     return result;
 }
 
-std::string DiagnosticsHolder::GetFullDiagnostic(Diagnostic* diagnostic) {
+std::string* DiagnosticsHolder::GetFullDiagnostic(Diagnostic* diagnostic) {
+    auto previousMsg = diagnostic->GetMessage();
+    if (previousMsg != nullptr){
+        return previousMsg;
+    }
     stringstream stream;
     stream << "[" << SeverityToString(diagnostic->GetSeverity()) << "] ";
     auto startPos = diagnostic->GetStartPosition();
@@ -108,7 +112,9 @@ std::string DiagnosticsHolder::GetFullDiagnostic(Diagnostic* diagnostic) {
     if (unformatted != ErrorMessages.end()){
         stream << PrettyDiagnostic(unformatted->second, diagnostic->GetArguments());
     }
-    return stream.str();
+    auto s = new string(stream.str());
+    diagnostic->SetMessage(s);
+    return s;
 }
 
 extern "C" {
@@ -120,7 +126,7 @@ extern "C" {
         return diagnostics->GetDiagnosticAt(position);
     }
 
-    const char* GetFullDiagnostic(DiagnosticsHolder* diagnostics, Diagnostic* diag){
-        return diagnostics ->GetFullDiagnostic(diag).c_str();
+    const char * GetFullDiagnostic(DiagnosticsHolder* diagnostics, Diagnostic* diag){
+        return diagnostics ->GetFullDiagnostic(diag)->c_str();
     }
 }
diff --git a/src/Diagnostics/DiagnosticsHolder.hpp b/src/Diagnostics/DiagnosticsHolder.hpp
index 695c279..6341153 100644
--- a/src/Diagnostics/DiagnosticsHolder.hpp
+++ b/src/Diagnostics/DiagnosticsHolder.hpp
@@ -58,7 +58,7 @@ namespace Porygon::Diagnostics {
             return _lineStarts[i];
         }
 
-        std::string GetFullDiagnostic(Diagnostic* diagnostic);
+        std::string* GetFullDiagnostic(Diagnostic* diagnostic);
     };
 }
 
diff --git a/tests/integration/DiagnosticsTests.cpp b/tests/integration/DiagnosticsTests.cpp
index 565dd05..17f3818 100644
--- a/tests/integration/DiagnosticsTests.cpp
+++ b/tests/integration/DiagnosticsTests.cpp
@@ -48,7 +48,7 @@ TEST_CASE( "Get full diagnostic message", "[integration]" ) {
     REQUIRE(script->Diagnostics -> HasErrors());
     auto diags = script->Diagnostics -> GetDiagnostics();
     auto msg = script->Diagnostics->GetFullDiagnostic(&diags[0]);
-    REQUIRE(msg == "[Error]  (2, 2) '\\x' is not a valid control character.");
+    REQUIRE(*msg == "[Error]  (2, 2) '\\x' is not a valid control character.");
     delete script;
 }