diff --git a/src/MultiPlayer/multiplaymgr.cxx b/src/MultiPlayer/multiplaymgr.cxx
index 0f5414c..f34aeeb 100644
--- a/src/MultiPlayer/multiplaymgr.cxx
+++ b/src/MultiPlayer/multiplaymgr.cxx
@@ -693,6 +693,8 @@ const unsigned int numProperties = (sizeof(sIdPropertyList) / sizeof(sIdProperty
 // Look up a property ID using binary search.
 namespace
 {
+  using namespace simgear;
+
   struct ComparePropertyId
   {
     bool operator()(const IdPropertyList& lhs,