diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1594c9a..3cc12d4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.29)
 project(cmpsc330hw2)
 
-set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD 11)
 
 add_executable(cmpsc330hw2 main.cpp)
diff --git a/main.cpp b/main.cpp
index 9798ac0..93e1776 100644
--- a/main.cpp
+++ b/main.cpp
@@ -98,12 +98,29 @@ bool isValidPlayer(char c) {
     return c >= 'A' && c <= 'Z' && c != 'X';
 }
 
-Moves serialize(const string &s) {
-    // TODO: add check for impossible board sizes
+string toString(int x) {
+    string result;
+    while (x) {
+        result.push_back(x % 10 + '0');
+        x /= 10;
+    }
+    reverse(result.begin(), result.end());
+    return result;
+}
 
+Moves serialize(const string &s) {
     Moves result;
     istringstream iss(s);
     iss >> result.x >> result.y;
+    if (result.x < 2 || result.y < 2) {
+        string err = "Invalid board size: ";
+        err.append(toString(result.x));
+        err.append("x");
+        err.append(toString(result.y));
+
+        throw invalid_argument(err);
+    }
+
     result.x <<= 1;
     result.y <<= 1;