diff --git a/simgear/props/propertyObject_test.cxx b/simgear/props/propertyObject_test.cxx
index b2c458ad..5bb4ae58 100644
--- a/simgear/props/propertyObject_test.cxx
+++ b/simgear/props/propertyObject_test.cxx
@@ -5,6 +5,9 @@
 #include <cassert>
 #include <cstring>
 
+// working around MSVC weirdness with props.hxx and SGMathFwd
+#include <simgear/math/SGMath.hxx>
+
 #include "propertyObject.hxx"
 
 #include <simgear/structure/exception.hxx>
diff --git a/simgear/props/props_test.cxx b/simgear/props/props_test.cxx
index b3109821..cd54ec50 100644
--- a/simgear/props/props_test.cxx
+++ b/simgear/props/props_test.cxx
@@ -6,6 +6,10 @@
 #include <simgear/compiler.h>
 
 #include <iostream>
+
+// working around MSVC weirdness with props.hxx and SGMathFwd
+#include <simgear/math/SGMath.hxx>
+
 #include "props.hxx"
 #include "props_io.hxx"