diff --git a/Source/Common/MemoryCommon.cpp b/Source/Common/MemoryCommon.cpp
index 3320503..6891ce5 100644
--- a/Source/Common/MemoryCommon.cpp
+++ b/Source/Common/MemoryCommon.cpp
@@ -651,7 +651,7 @@ std::string formatMemoryToString(const char* memory, const MemType type, const s
       if (c == '\0')
         break;
 
-      if (std::isprint(c))
+      if (std::isprint(static_cast<int>(static_cast<unsigned char>(c))))
       {
         text.push_back(c);
       }
diff --git a/Source/GUI/MainWindow.cpp b/Source/GUI/MainWindow.cpp
index 8010593..a78b408 100644
--- a/Source/GUI/MainWindow.cpp
+++ b/Source/GUI/MainWindow.cpp
@@ -588,7 +588,7 @@ void MainWindow::updateStatusBar()
     {
       for (char& c : gameID)
       {
-        if (!std::isprint(c))
+        if (!std::isprint(static_cast<int>(static_cast<unsigned char>(c))))
         {
           c = '?';
         }