diff --git a/ComditionVariableSample-video2.cpp b/ComditionVariableSample-video2.cpp
index cf3517d..182ceab 100644
--- a/ComditionVariableSample-video2.cpp
+++ b/ComditionVariableSample-video2.cpp
@@ -2,6 +2,7 @@
 #include <iostream>
 #include <queue>
 #include <functional>
+#include <mutex>
 using namespace std;
 
 template <typename T>
diff --git a/threadSamples-part1.cpp b/threadSamples-part1.cpp
index 4f56d82..f3bcacc 100644
--- a/threadSamples-part1.cpp
+++ b/threadSamples-part1.cpp
@@ -1,6 +1,7 @@
 #include <thread>
 #include <iostream>
 #include <functional>
+#include <mutex>
 using namespace std;
 
 template <typename T>
diff --git a/threadSamples-part3.cpp b/threadSamples-part3.cpp
index 2bebc87..5533bd1 100644
--- a/threadSamples-part3.cpp
+++ b/threadSamples-part3.cpp
@@ -3,6 +3,7 @@
 #include <queue>
 #include <functional>
 #include <fstream>
+#include <mutex>
 using namespace std;
 
 template <typename T>
diff --git a/threadsamples-video4.cpp b/threadsamples-video4.cpp
index 7caf7f7..4854e01 100644
--- a/threadsamples-video4.cpp
+++ b/threadsamples-video4.cpp
@@ -3,6 +3,7 @@
 #include <queue>
 #include <functional>
 #include <fstream>
+#include <mutex>
 using namespace std;
 
 template <typename T>