diff --git a/src/joystick/hidapi/SDL_hidapijoystick.c b/src/joystick/hidapi/SDL_hidapijoystick.c
index 27911a40db..634d91e7e1 100644
--- a/src/joystick/hidapi/SDL_hidapijoystick.c
+++ b/src/joystick/hidapi/SDL_hidapijoystick.c
@@ -1246,12 +1246,12 @@ static bool HIDAPI_IsEquivalentToDevice(Uint16 vendor_id, Uint16 product_id, SDL
     return false;
 }
 
-static bool HIDAPI_StartUpdatingDevices()
+static bool HIDAPI_StartUpdatingDevices(void)
 {
     return SDL_CompareAndSwapAtomicInt(&SDL_HIDAPI_updating_devices, false, true);
 }
 
-static void HIDAPI_FinishUpdatingDevices()
+static void HIDAPI_FinishUpdatingDevices(void)
 {
     SDL_SetAtomicInt(&SDL_HIDAPI_updating_devices, false);
 }
diff --git a/src/joystick/windows/SDL_rawinputjoystick_c.h b/src/joystick/windows/SDL_rawinputjoystick_c.h
index 4a79afd52c..6d6fa023a7 100644
--- a/src/joystick/windows/SDL_rawinputjoystick_c.h
+++ b/src/joystick/windows/SDL_rawinputjoystick_c.h
@@ -22,11 +22,11 @@
 #include "../../core/windows/SDL_windows.h"
 
 // Return true if the RawInput driver is enabled
-extern bool RAWINPUT_IsEnabled();
+extern bool RAWINPUT_IsEnabled(void);
 
 // Registers for input events
 extern int RAWINPUT_RegisterNotifications(HWND hWnd);
-extern int RAWINPUT_UnregisterNotifications();
+extern int RAWINPUT_UnregisterNotifications(void);
 
 // Returns 0 if message was handled
 extern LRESULT CALLBACK RAWINPUT_WindowProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
diff --git a/src/video/windows/SDL_windowsmouse.h b/src/video/windows/SDL_windowsmouse.h
index ba298b736f..4646a2ec10 100644
--- a/src/video/windows/SDL_windowsmouse.h
+++ b/src/video/windows/SDL_windowsmouse.h
@@ -29,6 +29,6 @@ extern HCURSOR SDL_cursor;
 extern void WIN_InitMouse(SDL_VideoDevice *_this);
 extern void WIN_QuitMouse(SDL_VideoDevice *_this);
 extern void WIN_SetCursorPos(int x, int y);
-extern void WIN_UpdateMouseSystemScale();
+extern void WIN_UpdateMouseSystemScale(void);
 
 #endif // SDL_windowsmouse_h_