diff --git a/main.cpp b/main.cpp
index 2e702e2..f55983a 100644
--- a/main.cpp
+++ b/main.cpp
@@ -124,7 +124,7 @@ void decode_mode() {
     if (input.empty())
       continue;
 
-    if (tolower(input[0]) == 'e')
+    if (input.size() == 1 && (input[0] == 'e' || input[0] == 'E'))
       return;
 
     string decoded_message;
@@ -176,7 +176,7 @@ void encode_mode() {
     if (input.empty())
       continue;
 
-    if (tolower(input[0]) == 'd')
+    if (input.size() == 1 && (input[0] == 'd' || input[0] == 'D'))
       return;
 
     cout << "\n";