diff --git a/include/tables/TableKeyNotDefinedException.h b/include/tables/TableKeyNotDefinedException.h
index 2ff4cf9dc1..a99ba9409f 100644
--- a/include/tables/TableKeyNotDefinedException.h
+++ b/include/tables/TableKeyNotDefinedException.h
@@ -21,7 +21,7 @@ class TableKeyNotDefinedException : public std::exception {
    */
   TableKeyNotDefinedException(llvm::StringRef key);
   ~TableKeyNotDefinedException() noexcept;
-  const char* what();
+  const char* what() const noexcept override;
 
  private:
   std::string msg;
diff --git a/src/tables/TableKeyNotDefinedException.cpp b/src/tables/TableKeyNotDefinedException.cpp
index 3fef63872d..31eb8b346d 100644
--- a/src/tables/TableKeyNotDefinedException.cpp
+++ b/src/tables/TableKeyNotDefinedException.cpp
@@ -12,6 +12,8 @@ TableKeyNotDefinedException::TableKeyNotDefinedException(llvm::StringRef key)
   msg += key;
 }
 
-const char* TableKeyNotDefinedException::what() { return msg.c_str(); }
+const char* TableKeyNotDefinedException::what() const noexcept {
+  return msg.c_str();
+}
 
 TableKeyNotDefinedException::~TableKeyNotDefinedException() noexcept {}