diff --git a/common/2d/bitmap.cpp b/common/2d/bitmap.cpp
index 39f06147b..27d44a1e6 100644
--- a/common/2d/bitmap.cpp
+++ b/common/2d/bitmap.cpp
@@ -64,7 +64,7 @@ grs_bitmap_ptr gr_create_bitmap_raw(const uint16_t w, const uint16_t h, RAIIdmem
 }
 
 // TODO: virtualize
-void gr_init_bitmap(grs_bitmap &bm, const bm_mode mode, const uint16_t x, const uint16_t y, const uint16_t w, const uint16_t h, const uint16_t bytesperline, const uint8_t *const data) noexcept
+void gr_init_bitmap(grs_bitmap &bm, const bm_mode mode, const uint16_t x, const uint16_t y, const uint16_t w, const uint16_t h, const uint16_t bytesperline, color_palette_index *const mdata) noexcept
 {
 	bm.bm_x = x;
 	bm.bm_y = y;
@@ -74,7 +74,7 @@ void gr_init_bitmap(grs_bitmap &bm, const bm_mode mode, const uint16_t x, const
 	bm.set_type(mode);
 	bm.bm_rowsize = bytesperline;
 
-	bm.bm_data = data;
+	bm.bm_mdata = mdata;
 #if DXX_USE_OGL
 	bm.bm_parent = nullptr;
 	bm.gltexture = nullptr;
diff --git a/common/include/fwd-gr.h b/common/include/fwd-gr.h
index 49eabae90..77dceb3b9 100644
--- a/common/include/fwd-gr.h
+++ b/common/include/fwd-gr.h
@@ -154,7 +154,7 @@ void gr_clear_canvas(grs_canvas &, color_t color);
 // Bitmap functions:
 
 // these are the two workhorses, the others just use these
-void gr_init_bitmap(grs_bitmap &bm, bm_mode mode, uint16_t x, uint16_t y, uint16_t w, uint16_t h, uint16_t bytesperline, const uint8_t *data) noexcept;
+void gr_init_bitmap(grs_bitmap &bm, bm_mode mode, uint16_t x, uint16_t y, uint16_t w, uint16_t h, uint16_t bytesperline, color_palette_index *data) noexcept;
 void gr_init_main_bitmap(grs_main_bitmap &bm, bm_mode mode, uint16_t x, uint16_t y, uint16_t w, uint16_t h, uint16_t bytesperline, RAIIdmem<uint8_t[]> data);
 void gr_init_sub_bitmap (grs_bitmap &bm, grs_bitmap &bmParent, uint16_t x, uint16_t y, uint16_t w, uint16_t h);