diff --git a/doc/lua_api.md b/doc/lua_api.md
index efe05e5d9..e7498ff04 100644
--- a/doc/lua_api.md
+++ b/doc/lua_api.md
@@ -456,6 +456,10 @@ i.e. without gamma-correction.
 
 Textures can be overlaid by putting a `^` between them.
 
+Warning: If the lower and upper pixels are both semi-transparent, this operation
+does *not* do alpha blending, and it is *not* associative. Otherwise it does
+alpha blending in srgb color space.
+
 Example:
 
     default_dirt.png^default_grass_side.png
diff --git a/src/client/imagesource.cpp b/src/client/imagesource.cpp
index 4bcfb9804..696159408 100644
--- a/src/client/imagesource.cpp
+++ b/src/client/imagesource.cpp
@@ -420,12 +420,11 @@ void blit_pixel(video::SColor src_col, video::SColor &dst_col)
 		return;
 	}
 	// A semi-transparent pixel is on top of a
-	// semi-transparent pixel -> general alpha compositing
-	u16 a_new_255 = src_a * 255 + (255 - src_a) * dst_a;
-	dst.r = (dst.r * (255 - src_a) * dst_a + src.r * src_a * 255) / a_new_255;
-	dst.g = (dst.g * (255 - src_a) * dst_a + src.g * src_a * 255) / a_new_255;
-	dst.b = (dst.b * (255 - src_a) * dst_a + src.b * src_a * 255) / a_new_255;
-	dst_a = (a_new_255 + 127) / 255;
+	// semi-transparent pixel -> weird overlaying
+	dst.r = (dst.r * (255 - src_a) + src.r * src_a) / 255;
+	dst.g = (dst.g * (255 - src_a) + src.g * src_a) / 255;
+	dst.b = (dst.b * (255 - src_a) + src.b * src_a) / 255;
+	dst_a = dst_a + (255 - dst_a) * src_a * src_a / (255 * 255);
 	dst_col.set(dst_a, dst.r, dst.g, dst.b);
 }