diff --git a/simgear/math/SGGeod.hxx b/simgear/math/SGGeod.hxx
index 8eddbe92..89461db8 100644
--- a/simgear/math/SGGeod.hxx
+++ b/simgear/math/SGGeod.hxx
@@ -19,6 +19,7 @@
 #define SGGeod_H
 
 #include <simgear/constants.h>
+#include <simgear/math/SGVec3.hxx>
 
 // #define SG_GEOD_NATIVE_DEGREE
 
diff --git a/simgear/math/SGVec2.hxx b/simgear/math/SGVec2.hxx
index 1ed150d8..49d8b619 100644
--- a/simgear/math/SGVec2.hxx
+++ b/simgear/math/SGVec2.hxx
@@ -20,6 +20,10 @@
 
 #include <iosfwd>
 
+#include <simgear/math/SGLimits.hxx>
+#include <simgear/math/SGMisc.hxx>
+#include <simgear/math/SGMathFwd.hxx>
+
 /// 2D Vector Class
 template<typename T>
 class SGVec2 {
diff --git a/simgear/math/SGVec3.hxx b/simgear/math/SGVec3.hxx
index b0f6b206..68c9c83b 100644
--- a/simgear/math/SGVec3.hxx
+++ b/simgear/math/SGVec3.hxx
@@ -20,6 +20,9 @@
 
 #include <iosfwd>
 
+#include <simgear/math/SGVec2.hxx>
+#include <simgear/math/SGGeodesy.hxx>
+
 /// 3D Vector Class
 template<typename T>
 class SGVec3 {