diff --git a/Source/simba.target.pas b/Source/simba.target.pas
index 177838fea..a4aad9847 100644
--- a/Source/simba.target.pas
+++ b/Source/simba.target.pas
@@ -357,6 +357,8 @@ procedure TSimbaTarget.SetEIOS(FileName, Args: String);
 
   FMethods.GetDimensions := @EIOSTarget_GetDimensions;
   FMethods.GetImageData := @EIOSTarget_GetImageData;
+
+  FMethods.IsValid := @EIOSTarget_IsValid;
 end;
 
 procedure TSimbaTarget.SetPlugin(FileName, Args: String);
@@ -364,6 +366,7 @@ procedure TSimbaTarget.SetPlugin(FileName, Args: String);
   ChangeTarget(ETargetType.PLUGIN);
 
   FTargetPlugin := LoadPluginTarget(FileName, Args);
+  FTarget := @FTargetPlugin;
 
   FMethods.KeyDown := @PluginTarget_KeyDown;
   FMethods.KeyUp := @PluginTarget_KeyUp;
@@ -379,6 +382,8 @@ procedure TSimbaTarget.SetPlugin(FileName, Args: String);
 
   FMethods.GetDimensions := @PluginTarget_GetDimensions;
   FMethods.GetImageData := @PluginTarget_GetImageData;
+
+  FMethods.IsValid := @PluginTarget_IsValid;
 end;
 
 procedure TSimbaTarget.SetPlugin(FileName, Args: String; out DebugImage: TSimbaExternalImage);
diff --git a/Source/targets/simba.target_eios.pas b/Source/targets/simba.target_eios.pas
index d7e880444..c1570bb9b 100644
--- a/Source/targets/simba.target_eios.pas
+++ b/Source/targets/simba.target_eios.pas
@@ -95,6 +95,8 @@ procedure EIOSTarget_MouseDown(Target: Pointer; Button: EMouseButton);
 procedure EIOSTarget_MouseUp(Target: Pointer; Button: EMouseButton);
 procedure EIOSTarget_MouseScroll(Target: Pointer; Scrolls: Integer);
 
+function EIOSTarget_IsValid(Target: Pointer): Boolean;
+
 implementation
 
 uses
@@ -253,6 +255,11 @@ procedure EIOSTarget_MouseScroll(Target: Pointer; Scrolls: Integer);
   end;
 end;
 
+function EIOSTarget_IsValid(Target: Pointer): Boolean;
+begin
+  Result := True;
+end;
+
 procedure EIOSTarget_KeyDown(Target: Pointer; Key: EKeyCode);
 begin
   with PEIOSTarget(Target)^ do
diff --git a/Source/targets/simba.target_plugin.pas b/Source/targets/simba.target_plugin.pas
index c4d4e05b5..6a1812b10 100644
--- a/Source/targets/simba.target_plugin.pas
+++ b/Source/targets/simba.target_plugin.pas
@@ -53,11 +53,19 @@ procedure PluginTarget_KeyUp(Target: Pointer; Key: EKeyCode);
 procedure PluginTarget_KeySend(Target: Pointer; Key: Char; KeyDownTime, KeyUpTime, ModifierDownTime, ModifierUpTime: Integer);
 function PluginTarget_KeyPressed(Target: Pointer; Key: EKeyCode): Boolean;
 
+function PluginTarget_IsValid(Target: Pointer): Boolean;
+
 implementation
 
 uses
   simba.env, simba.files, simba.script_pluginloader;
 
+procedure CheckExported(const MethodName: String; const Method: Pointer); inline;
+begin
+  if (Method = nil) then
+    SimbaException('SimbaPluginTarget: "' + MethodName + '" is not exported');
+end;
+
 function Load(AFileName: String): TSimbaPluginTarget;
 begin
   Result := Default(TSimbaPluginTarget);
@@ -97,85 +105,148 @@ function Load(AFileName: String): TSimbaPluginTarget;
 function LoadPluginTarget(FileName, Args: String): TSimbaPluginTarget;
 begin
   Result := Load(FileName);
-  Result.Target := Result.Request(PChar(Args));
+  with Result do
+  begin
+    CheckExported('SimbaPluginTarget_Request', Request);
+
+    Result.Target := Result.Request(PChar(Args));
+  end;
 end;
 
 function LoadPluginTarget(FileName, Args: String; out DebugImage: TSimbaExternalImage): TSimbaPluginTarget;
 begin
   Result := Load(FileName);
-  Result.Target := Result.RequestWithDebugImage(PChar(Args), DebugImage);
+  with Result do
+  begin
+    CheckExported('SimbaPluginTarget_RequestWithDebugImage', RequestWithDebugImage);
+
+    Target := Result.RequestWithDebugImage(PChar(Args), DebugImage);
+  end;
 end;
 
 procedure PluginTarget_GetDimensions(Target: Pointer; out W, H: Integer);
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_GetDimensions', GetDimensions);
+
     GetDimensions(Target, W, H);
+  end;
 end;
 
 function PluginTarget_GetImageData(Target: Pointer; X, Y, Width, Height: Integer; var Data: PColorBGRA; var DataWidth: Integer): Boolean;
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_GetImageData', GetImageData);
+
     Result := GetImageData(Target, X, Y, Width, Height, Data, DataWidth);
+  end;
 end;
 
 function PluginTarget_MousePressed(Target: Pointer; Button: EMouseButton): Boolean;
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_MousePressed', MousePressed);
+
     Result := MousePressed(Target, Integer(Button));
+  end;
 end;
 
 function PluginTarget_MousePosition(Target: Pointer): TPoint;
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_MousePosition', MousePosition);
+
     Result := MousePosition(Target);
+  end;
 end;
 
 procedure PluginTarget_MouseTeleport(Target: Pointer; P: TPoint);
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_MouseTeleport', MouseTeleport);
+
     MouseTeleport(Target, P);
+  end;
 end;
 
 procedure PluginTarget_MouseUp(Target: Pointer; Button: EMouseButton);
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_MouseUp', MouseUp);
+
     MouseUp(Target, Integer(Button));
+  end;
 end;
 
 procedure PluginTarget_MouseDown(Target: Pointer; Button: EMouseButton);
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_MouseDown', MouseDown);
+
     MouseDown(Target, Integer(Button));
+  end;
 end;
 
 procedure PluginTarget_MouseScroll(Target: Pointer; Scrolls: Integer);
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_MouseScroll', MouseScroll);
+
     MouseScroll(Target, Scrolls);
+  end;
 end;
 
 procedure PluginTarget_KeyDown(Target: Pointer; Key: EKeyCode);
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_KeyDown', KeyDown);
+
     KeyDown(Target, Integer(Key));
+  end;
 end;
 
 procedure PluginTarget_KeyUp(Target: Pointer; Key: EKeyCode);
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_KeyUp', KeyUp);
+
     KeyUp(Target, Integer(Key));
+  end;
 end;
 
 procedure PluginTarget_KeySend(Target: Pointer; Key: Char; KeyDownTime, KeyUpTime, ModifierDownTime, ModifierUpTime: Integer);
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_KeySend', KeySend);
+
     KeySend(Target, Key, KeyDownTime, KeyUpTime, ModifierDownTime, ModifierUpTime);
+  end;
 end;
 
 function PluginTarget_KeyPressed(Target: Pointer; Key: EKeyCode): Boolean;
 begin
   with PSimbaPluginTarget(Target)^ do
+  begin
+    CheckExported('SimbaPluginTarget_KeyPressed', KeyPressed);
+
     Result := KeyPressed(Target, Integer(Key));
+  end;
+end;
+
+function PluginTarget_IsValid(Target: Pointer): Boolean;
+begin
+  Result := True;
 end;
 
 end.