diff --git a/printer-linter/src/printerlinter/diagnostic.py b/printer-linter/src/printerlinter/diagnostic.py
index d5eb237c29..ac6e3b829e 100644
--- a/printer-linter/src/printerlinter/diagnostic.py
+++ b/printer-linter/src/printerlinter/diagnostic.py
@@ -22,7 +22,7 @@ class Diagnostic:
         self.level = level
         self.replacements = replacements
 
-    def toDict(self) -> dict:
+    def toDict(self) -> Dict[str, Any[str, int, List[Replacements]]]:
         return {"DiagnosticName": self.diagnostic_name,
                 "DiagnosticMessage": {
                     "Message": self.message,