diff --git a/simgear/debug/logtest.cxx b/simgear/debug/logtest.cxx
index afa5ddcc..07a6501a 100644
--- a/simgear/debug/logtest.cxx
+++ b/simgear/debug/logtest.cxx
@@ -1,5 +1,5 @@
 #include <string>
-#include "Debug/logstream.hxx"
+#include <simgear/debug/logstream.hxx>
 
 class Test {
 
diff --git a/simgear/math/interpolater.hxx b/simgear/math/interpolater.hxx
index 0df566a9..393e39ff 100644
--- a/simgear/math/interpolater.hxx
+++ b/simgear/math/interpolater.hxx
@@ -35,7 +35,7 @@
 
 #include <simgear/compiler.h>
 
-#include "simgear/structure/SGReferenced.hxx"
+#include <simgear/structure/SGReferenced.hxx>
 
 #include <map>
 
diff --git a/simgear/misc/tabbed_values.cxx b/simgear/misc/tabbed_values.cxx
index dc4d34bc..07ed2063 100644
--- a/simgear/misc/tabbed_values.cxx
+++ b/simgear/misc/tabbed_values.cxx
@@ -21,10 +21,10 @@
 // $Id$
 
 #include <cstdlib>
+#include <assert.h>
 
 #include "tabbed_values.hxx"
 
-#include "assert.h"
 
 SGTabbedValues::SGTabbedValues(const char *line) :
 	_line(line)
diff --git a/simgear/threads/SGThread.cxx b/simgear/threads/SGThread.cxx
index d786c24a..c7a841b0 100644
--- a/simgear/threads/SGThread.cxx
+++ b/simgear/threads/SGThread.cxx
@@ -11,7 +11,7 @@
 #  include <sys/time.h>
 #endif
 #if _MSC_VER >= 1300
-#  include "winsock2.h"
+#  include <winsock2.h>
 #endif
 
 #include "SGThread.hxx"
diff --git a/simgear/xml/xmldef.h b/simgear/xml/xmldef.h
index 49ce9ed6..81de339b 100644
--- a/simgear/xml/xmldef.h
+++ b/simgear/xml/xmldef.h
@@ -53,7 +53,7 @@ particular environments. */
 
 #ifdef MOZILLA
 
-#include "nspr.h"
+#include <nspr.h>
 #define malloc(x) PR_Malloc(x)
 #define realloc(x, y) PR_Realloc((x), (y))
 #define calloc(x, y) PR_Calloc((x),(y))