diff --git a/src/AIModel/submodel.cxx b/src/AIModel/submodel.cxx
index 1327c3c28..ca88233d9 100644
--- a/src/AIModel/submodel.cxx
+++ b/src/AIModel/submodel.cxx
@@ -44,10 +44,6 @@ FGSubmodelMgr::FGSubmodelMgr()
     _found_sub = true;
 }
 
-FGSubmodelMgr::~FGSubmodelMgr()
-{
-}
-
 FGAIManager* FGSubmodelMgr::aiManager()
 {
    return globals->get_subsystem<FGAIManager>();
diff --git a/src/AIModel/submodel.hxx b/src/AIModel/submodel.hxx
index b368f06f5..09d149b71 100644
--- a/src/AIModel/submodel.hxx
+++ b/src/AIModel/submodel.hxx
@@ -3,9 +3,10 @@
 //
 // This file is in the Public Domain and comes with no warranty.
 
+#pragma once
 
-#ifndef __SYSTEMS_SUBMODEL_HXX
-#define __SYSTEMS_SUBMODEL_HXX 1
+#include <string>
+#include <vector>
 
 #include <simgear/props/props.hxx>
 #include <simgear/structure/subsystem_mgr.hxx>
@@ -13,9 +14,6 @@
 
 #include <Autopilot/inputvalue.hxx>
 
-#include <vector>
-#include <string>
-
 class FGAIBase;
 class FGAIManager;
 
@@ -94,7 +92,7 @@ public:
     }   IC_struct;
 
     FGSubmodelMgr();
-    ~FGSubmodelMgr() override;
+    virtual ~FGSubmodelMgr() = default;
 
     // Subsystem API.
     void bind() override;
@@ -189,5 +187,3 @@ private:
     SGVec3d getCartOffsetPos(submodel* sm) const;
     void setOffsetPos(submodel* sm);
 };
-
-#endif // __SYSTEMS_SUBMODEL_HXX