diff --git a/extras/conf/udb/Includes/SRB222_misc.cfg b/extras/conf/udb/Includes/SRB222_misc.cfg
index 1b4fb4b4b..50c83e456 100644
--- a/extras/conf/udb/Includes/SRB222_misc.cfg
+++ b/extras/conf/udb/Includes/SRB222_misc.cfg
@@ -70,6 +70,7 @@ linedefrenderstyles
 	subtract = "Subtract";
 	reversesubtract = "Reverse subtract";
 	modulate = "Modulate";
+	fog = "Fog";
 }
 
 sectorflags
diff --git a/src/deh_tables.c b/src/deh_tables.c
index 730ae959b..cfc98f631 100644
--- a/src/deh_tables.c
+++ b/src/deh_tables.c
@@ -4898,6 +4898,7 @@ struct int_const_s const INT_CONST[] = {
 	{"AST_REVERSESUBTRACT",AST_REVERSESUBTRACT},
 	{"AST_MODULATE",AST_MODULATE},
 	{"AST_OVERLAY",AST_OVERLAY},
+	{"AST_FOG",AST_FOG},
 
 	// Render flags
 	{"RF_HORIZONTALFLIP",RF_HORIZONTALFLIP},
diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index a1dd53eb7..13b2a39c3 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -1454,13 +1454,13 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 				case 221:
 				case 253:
 				case 256:
-					if (gl_linedef->blendmode)
+					if (gl_linedef->blendmode != AST_FOG)
 						blendmode = HWR_SurfaceBlend(gl_linedef->blendmode, R_GetLinedefTransTable(gl_linedef->alpha), &Surf);
 					else
 						blendmode = PF_Translucent;
 					break;
 				default:
-					if (gl_linedef->blendmode)
+					if (gl_linedef->blendmode != AST_FOG)
 					{
 						if (gl_linedef->alpha >= 0 && gl_linedef->alpha < FRACUNIT)
 							blendmode = HWR_SurfaceBlend(gl_linedef->blendmode, R_GetLinedefTransTable(gl_linedef->alpha), &Surf);
diff --git a/src/p_setup.c b/src/p_setup.c
index 9a2e14cab..4f21922a0 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -1713,6 +1713,8 @@ static void ParseTextmapLinedefParameter(UINT32 i, char *param, char *val)
 			lines[i].blendmode = AST_REVERSESUBTRACT;
 		else if (fastcmp(val, "modulate"))
 			lines[i].blendmode = AST_MODULATE;
+		if (fastcmp(val, "fog"))
+			lines[i].blendmode = AST_FOG;
 	}
 	else if (fastcmp(param, "executordelay"))
 		lines[i].executordelay = atol(val);
@@ -3337,6 +3339,9 @@ static void P_ConvertBinaryMap(void)
 				lines[i].args[4] |= TMSC_BACKTOFRONTCEILING;
 			lines[i].special = 720;
 			break;
+		case 909: //Fog wall
+			lines[i].blendmode = AST_FOG;
+			break;
 		default:
 			break;
 		}
diff --git a/src/r_defs.h b/src/r_defs.h
index 3c2178937..fa63de400 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -716,7 +716,7 @@ typedef struct
 #endif
 
 // Possible alpha types for a patch.
-enum patchalphastyle {AST_COPY, AST_TRANSLUCENT, AST_ADD, AST_SUBTRACT, AST_REVERSESUBTRACT, AST_MODULATE, AST_OVERLAY};
+enum patchalphastyle {AST_COPY, AST_TRANSLUCENT, AST_ADD, AST_SUBTRACT, AST_REVERSESUBTRACT, AST_MODULATE, AST_OVERLAY, AST_FOG};
 
 typedef enum
 {
diff --git a/src/r_segs.c b/src/r_segs.c
index 4460f9f90..2459436b5 100644
--- a/src/r_segs.c
+++ b/src/r_segs.c
@@ -155,7 +155,13 @@ void R_RenderMaskedSegRange(drawseg_t *ds, INT32 x1, INT32 x2)
 	if (!ldef->alpha)
 		return;
 
-	if (ldef->blendmode)
+	if (ldef->blendmode == AST_FOG)
+	{
+		colfunc = colfuncs[COLDRAWFUNC_FOG];
+		windowtop = frontsector->ceilingheight;
+		windowbottom = frontsector->floorheight;
+	}
+	else if (ldef->blendmode)
 	{
 		if (ldef->alpha == NUMTRANSMAPS || ldef->blendmode == AST_MODULATE)
 			dc_transmap = R_GetBlendTable(ldef->blendmode, 0);
@@ -168,12 +174,6 @@ void R_RenderMaskedSegRange(drawseg_t *ds, INT32 x1, INT32 x2)
 		dc_transmap = R_GetTranslucencyTable(R_GetLinedefTransTable(ldef->alpha));
 		colfunc = colfuncs[COLDRAWFUNC_FUZZY];
 	}
-	else if (ldef->special == 909)
-	{
-		colfunc = colfuncs[COLDRAWFUNC_FOG];
-		windowtop = frontsector->ceilingheight;
-		windowbottom = frontsector->floorheight;
-	}
 	else
 		colfunc = colfuncs[BASEDRAWFUNC];