diff --git a/cpp/QrCode.cpp b/cpp/QrCode.cpp
index 6d6913e..aca04b0 100644
--- a/cpp/QrCode.cpp
+++ b/cpp/QrCode.cpp
@@ -28,6 +28,10 @@
 #include "BitBuffer.hpp"
 #include "QrCode.hpp"
 
+using std::int8_t;
+using std::uint8_t;
+using std::size_t;
+
 
 namespace qrcodegen {
 
diff --git a/cpp/QrCodeGeneratorDemo.cpp b/cpp/QrCodeGeneratorDemo.cpp
index e0719c1..d730bb4 100644
--- a/cpp/QrCodeGeneratorDemo.cpp
+++ b/cpp/QrCodeGeneratorDemo.cpp
@@ -31,6 +31,7 @@
 #include <vector>
 #include "QrCode.hpp"
 
+using std::uint8_t;
 using qrcodegen::QrCode;
 using qrcodegen::QrSegment;
 
diff --git a/cpp/QrSegment.cpp b/cpp/QrSegment.cpp
index c2a4667..61c22fd 100644
--- a/cpp/QrSegment.cpp
+++ b/cpp/QrSegment.cpp
@@ -26,6 +26,8 @@
 #include "BitBuffer.hpp"
 #include "QrSegment.hpp"
 
+using std::uint8_t;
+
 
 namespace qrcodegen {