diff --git a/ois/demos/FFConsoleDemo.cpp b/ois/demos/FFConsoleDemo.cpp
index 9e996aa..d07b0ee 100644
--- a/ois/demos/FFConsoleDemo.cpp
+++ b/ois/demos/FFConsoleDemo.cpp
@@ -1,3 +1,5 @@
+#include <unistd.h>
+
 #include "OIS.h"
 
 #include <math.h>
diff --git a/ois/demos/OISConsole.cpp b/ois/demos/OISConsole.cpp
index 86f325a..7c5ab25 100644
--- a/ois/demos/OISConsole.cpp
+++ b/ois/demos/OISConsole.cpp
@@ -1,4 +1,7 @@
 //////////////////////////////// OS Nuetral Headers ////////////////
+
+#include <unistd.h>
+
 #include "OISInputManager.h"
 #include "OISException.h"
 #include "OISKeyboard.h"
diff --git a/ois/src/linux/LinuxForceFeedback.cpp b/ois/src/linux/LinuxForceFeedback.cpp
index 466a989..abc5744 100644
--- a/ois/src/linux/LinuxForceFeedback.cpp
+++ b/ois/src/linux/LinuxForceFeedback.cpp
@@ -20,6 +20,9 @@ restrictions:
 
     3. This notice may not be removed or altered from any source distribution.
 */
+
+#include <unistd.h>
+
 #include "linux/LinuxForceFeedback.h"
 #include "OISException.h"
 
diff --git a/ois/src/linux/LinuxJoyStickEvents.cpp b/ois/src/linux/LinuxJoyStickEvents.cpp
index 35c14ca..cc36663 100644
--- a/ois/src/linux/LinuxJoyStickEvents.cpp
+++ b/ois/src/linux/LinuxJoyStickEvents.cpp
@@ -20,6 +20,9 @@ restrictions:
 
     3. This notice may not be removed or altered from any source distribution.
 */
+
+#include <unistd.h>
+
 #include "OISConfig.h"
 
 #include "linux/LinuxJoyStickEvents.h"