diff --git a/main.cpp b/main.cpp
index e095695..f04284b 100644
--- a/main.cpp
+++ b/main.cpp
@@ -42,16 +42,21 @@ string read_input(const string &prompt) {
 
 class MorseDecoder {
 private:
-  map<string, char> morse_to_char;
-
-public:
-  MorseDecoder() {
-    for (const auto &[ch, code] : morse_map) {
-      morse_to_char[code] = ch;
+  static const map<string, char> &get_morse_to_char() {
+    static map<string, char> morse_to_char;
+    static bool initialized = false;
+    if (!initialized) {
+      for (const auto &[ch, code] : morse_map) {
+        morse_to_char[code] = ch;
+      }
+      initialized = true;
     }
+    return morse_to_char;
   }
 
+public:
   char decode(const string &morse) {
+    const auto &morse_to_char = get_morse_to_char();
     auto it = morse_to_char.find(morse);
     return it != morse_to_char.end() ? it->second : '?';
   }