diff --git a/Machines/AtariST/AtariST.cpp b/Machines/AtariST/AtariST.cpp
index 5dbfb7de7..f42d10365 100644
--- a/Machines/AtariST/AtariST.cpp
+++ b/Machines/AtariST/AtariST.cpp
@@ -202,6 +202,11 @@ class IntelligentKeyboard:
 		}
 
 		void interrogate_mouse_position() {
+			output_byte(0x00);	// 0000dcba; a = right button down since last interrogation, b = right button up since, c/d = left button.
+			output_byte(0x00);	// x motion: MSB, LSB
+			output_byte(0x00);
+			output_byte(0x00);	// y motion: MSB, LSB
+			output_byte(0x00);
 		}
 
 		// MARK: - Joystick commands.