diff --git a/src/common/textures/formats/pngtexture.cpp b/src/common/textures/formats/pngtexture.cpp
index 48eb2437c..74474dede 100644
--- a/src/common/textures/formats/pngtexture.cpp
+++ b/src/common/textures/formats/pngtexture.cpp
@@ -360,7 +360,8 @@ void FPNGTexture::ReadAlphaRemap(FileReader *lump, uint8_t *alpharemap)
 		uint8_t r = lump->ReadUInt8();
 		uint8_t g = lump->ReadUInt8();
 		uint8_t b = lump->ReadUInt8();
-		alpharemap[i] = PaletteMap[i] == 0 ? 0 : Luminance(r, g, b);
+		int ti = PaletteMap ? PaletteMap[i] : i;
+		alpharemap[i] = ti == 0 ? 0 : Luminance(r, g, b);
 	}
 	lump->Seek(p, FileReader::SeekSet);
 }