diff --git a/src/blitter/40bpp_anim.cpp b/src/blitter/40bpp_anim.cpp
--- a/src/blitter/40bpp_anim.cpp
+++ b/src/blitter/40bpp_anim.cpp
@@ -11,6 +11,7 @@
 #include "../zoom_func.h"
 #include "../settings_type.h"
 #include "../video/video_driver.hpp"
+#include "../palette_func.h"
 #include "40bpp_anim.hpp"
 #include "common.hpp"
 
@@ -234,10 +235,6 @@ inline void Blitter_40bppAnim::Draw(cons
 					break;
 
 				case BM_TRANSPARENT:
-					/* TODO -- We make an assumption here that the remap in fact is transparency, not some colour.
-					 *  This is never a problem with the code we produce, but newgrfs can make it fail... or at least:
-					 *  we produce a result the newgrf maker didn't expect ;) */
-
 					/* Make the current colour a bit more black, so it looks like this image is transparent */
 					src_n += n;
 					if (src_px->a == 255) {
@@ -263,6 +260,28 @@ inline void Blitter_40bppAnim::Draw(cons
 					}
 					break;
 
+				case BM_TRANSPARENT_REMAP:
+					/* Apply custom transparency remap. */
+					src_n += n;
+					if (src_px->a != 0) {
+						src_px += n;
+						do {
+							if (*anim != 0) {
+								*anim = bp->remap[*anim];
+							} else {
+								*dst = this->LookupColourInPalette(bp->remap[GetNearestColourIndex(*dst)]);
+								*anim = 0;
+							}
+							anim++;
+							dst++;
+						} while (--n != 0);
+					} else {
+						dst += n;
+						anim += n;
+						src_px += n;
+					}
+					break;
+
 				default:
 					if (src_px->a == 255) {
 						do {
@@ -323,6 +342,7 @@ void Blitter_40bppAnim::Draw(Blitter::Bl
 		case BM_NORMAL:       Draw<BM_NORMAL>      (bp, zoom); return;
 		case BM_COLOUR_REMAP: Draw<BM_COLOUR_REMAP>(bp, zoom); return;
 		case BM_TRANSPARENT:  Draw<BM_TRANSPARENT> (bp, zoom); return;
+		case BM_TRANSPARENT_REMAP: Draw<BM_TRANSPARENT_REMAP>(bp, zoom); return;
 		case BM_CRASH_REMAP:  Draw<BM_CRASH_REMAP> (bp, zoom); return;
 		case BM_BLACK_REMAP:  Draw<BM_BLACK_REMAP> (bp, zoom); return;
 	}