diff --git a/Core/apu.h b/Core/apu.h
index 57c5976..9c9afc8 100644
--- a/Core/apu.h
+++ b/Core/apu.h
@@ -184,7 +184,6 @@ void GB_apu_div_secondary_event(GB_gameboy_t *gb);
 void GB_apu_init(GB_gameboy_t *gb);
 void GB_apu_run(GB_gameboy_t *gb);
 void GB_apu_update_cycles_per_sample(GB_gameboy_t *gb);
-void GB_borrow_sgb_border(GB_gameboy_t *gb);
 #endif
 
 #endif /* apu_h */
diff --git a/Core/gb.h b/Core/gb.h
index f0b3b16..4ac977e 100644
--- a/Core/gb.h
+++ b/Core/gb.h
@@ -892,5 +892,9 @@ unsigned GB_get_player_count(GB_gameboy_t *gb);
 // `title` must be at least 17 bytes in size
 void GB_get_rom_title(GB_gameboy_t *gb, char *title);
 uint32_t GB_get_rom_crc32(GB_gameboy_t *gb);
+
+#ifdef GB_INTERNAL
+void GB_borrow_sgb_border(GB_gameboy_t *gb);
+#endif
     
 #endif /* GB_h */