diff --git a/src/osgDB/DynamicLibrary.cpp b/src/osgDB/DynamicLibrary.cpp
index decde808b..cfc264767 100644
--- a/src/osgDB/DynamicLibrary.cpp
+++ b/src/osgDB/DynamicLibrary.cpp
@@ -20,9 +20,9 @@
 #endif
 
 #if defined(WIN32) && !defined(__CYGWIN__)
-#include <Io.h>
-#include <Windows.h>
-#include <Winbase.h>
+#include <io.h>
+#include <windows.h>
+#include <winbase.h>
 #elif defined(__APPLE__) && defined(APPLE_PRE_10_3)
 #include <mach-o/dyld.h>
 #else // all other unix
diff --git a/src/osgDB/FileUtils.cpp b/src/osgDB/FileUtils.cpp
index 7fb17061c..526f784cb 100644
--- a/src/osgDB/FileUtils.cpp
+++ b/src/osgDB/FileUtils.cpp
@@ -16,9 +16,9 @@
 // for now, the above include is commented out, and the below code takes precedence.
 
 #if defined(WIN32) && !defined(__CYGWIN__)
-    #include <Io.h>
-    #include <Windows.h>
-    #include <Winbase.h>
+    #include <io.h>
+    #include <windows.h>
+    #include <winbase.h>
     #include <sys/types.h>
     #include <sys/stat.h>
     #include <direct.h> // for _mkdir
diff --git a/src/osgPlugins/cfg/CameraConfig.cpp b/src/osgPlugins/cfg/CameraConfig.cpp
index 39718a59a..58a54bc7b 100644
--- a/src/osgPlugins/cfg/CameraConfig.cpp
+++ b/src/osgPlugins/cfg/CameraConfig.cpp
@@ -16,9 +16,9 @@
 #include <osg/io_utils>
 
 #if defined(WIN32) && !defined(__CYGWIN__)
-    #include <Io.h>
-    #include <Windows.h>
-    #include <Winbase.h>
+    #include <io.h>
+    #include <windows.h>
+    #include <winbase.h>
     // set up for windows so acts just like unix access().
     #define F_OK 4
 #else // unix
diff --git a/src/osgPlugins/net/sockstream.h b/src/osgPlugins/net/sockstream.h
index 9a2e7a168..846b62624 100644
--- a/src/osgPlugins/net/sockstream.h
+++ b/src/osgPlugins/net/sockstream.h
@@ -48,7 +48,7 @@
 #  define SOCKET_ERROR -1
 #else
 #  include <windows.h>
-#  include <Wininet.h>
+#  include <wininet.h>
 //#  include <errno.h>
 #ifdef _MSC_VER 
 #  pragma comment(lib, "Wininet")