diff --git a/src/Aircraft/replay.cxx b/src/Aircraft/replay.cxx
index 961a41506..78df737a3 100644
--- a/src/Aircraft/replay.cxx
+++ b/src/Aircraft/replay.cxx
@@ -123,4 +123,5 @@ void FGReplay::resetStatisticsProperties()
 
 
 // Register the subsystem.
-SGSubsystemMgr::Registrant<FGReplay> registrantFGReplay;
+SGSubsystemMgr::Registrant<FGReplay> registrantFGReplay(
+    SGSubsystemMgr::POST_FDM);
diff --git a/src/Instrumentation/HUD/HUD.cxx b/src/Instrumentation/HUD/HUD.cxx
index 059642efc..1dfee9e8e 100644
--- a/src/Instrumentation/HUD/HUD.cxx
+++ b/src/Instrumentation/HUD/HUD.cxx
@@ -649,7 +649,8 @@ void HUDText::draw()
 
 
 // Register the subsystem.
-SGSubsystemMgr::Registrant<HUD> registrantHUD;
+SGSubsystemMgr::Registrant<HUD> registrantHUD(
+    SGSubsystemMgr::DISPLAY);
 
 
 void TextList::align(const char *s, int align, float *x, float *y,
diff --git a/src/Network/fgcom.cxx b/src/Network/fgcom.cxx
index 2cf67e871..1e9d7a5f8 100644
--- a/src/Network/fgcom.cxx
+++ b/src/Network/fgcom.cxx
@@ -745,4 +745,5 @@ bool FGCom::isInRange(const double &freq) const
 
 
 // Register the subsystem.
-SGSubsystemMgr::Registrant<FGCom> registrantFGCom;
+SGSubsystemMgr::Registrant<FGCom> registrantFGCom(
+        SGSubsystemMgr::SOUND);