diff --git a/src/gl/renderer/gl_renderstate.cpp b/src/gl/renderer/gl_renderstate.cpp
index 0cc80d073..7664db1c5 100644
--- a/src/gl/renderer/gl_renderstate.cpp
+++ b/src/gl/renderer/gl_renderstate.cpp
@@ -145,6 +145,7 @@ bool FGLRenderState::ApplyShader()
 	activeShader->muLightIndex.Set(-1);
 	activeShader->muClipSplit.Set(mClipSplit);
 	activeShader->muSpecularMaterial.Set(mGlossiness, mSpecularLevel);
+	activeShader->muAddColor.Set(mAddColor); // Can this be done without a shader?
 
 	if (mGlowEnabled)
 	{
diff --git a/src/gl/shaders/gl_shader.cpp b/src/gl/shaders/gl_shader.cpp
index cc9811622..0dedd6966 100644
--- a/src/gl/shaders/gl_shader.cpp
+++ b/src/gl/shaders/gl_shader.cpp
@@ -241,6 +241,7 @@ bool FShader::Load(const char * name, const char * vert_prog_lump, const char *
 	i_data += "uniform vec4 uObjectColor;\n";
 	i_data += "uniform vec4 uObjectColor2;\n";
 	i_data += "uniform vec4 uDynLightColor;\n";
+	i_data += "uniform vec4 uAddColor;\n";
 	i_data += "uniform vec4 uFogColor;\n";
 	i_data += "uniform float uDesaturationFactor;\n";
 	i_data += "uniform float uInterpolationFactor;\n";
@@ -534,6 +535,7 @@ bool FShader::Load(const char * name, const char * vert_prog_lump, const char *
 	muInterpolationFactor.Init(hShader, "uInterpolationFactor");
 	muAlphaThreshold.Init(hShader, "uAlphaThreshold");
 	muSpecularMaterial.Init(hShader, "uSpecularMaterial");
+	muAddColor.Init(hShader, "uAddColor");
 	muTimer.Init(hShader, "timer");
 
 	lights_index = glGetUniformLocation(hShader, "lights");
diff --git a/src/gl/shaders/gl_shader.h b/src/gl/shaders/gl_shader.h
index cc1dece32..c9f4ce72c 100644
--- a/src/gl/shaders/gl_shader.h
+++ b/src/gl/shaders/gl_shader.h
@@ -245,6 +245,7 @@ class FShader
 	FBufferedUniform4f muDynLightColor;
 	FBufferedUniformPE muObjectColor;
 	FBufferedUniformPE muObjectColor2;
+	FBufferedUniformPE muAddColor;
 	FUniform4f muGlowBottomColor;
 	FUniform4f muGlowTopColor;
 	FUniform4f muGlowBottomPlane;
diff --git a/src/hwrenderer/scene/hw_drawstructs.h b/src/hwrenderer/scene/hw_drawstructs.h
index ae89d65de..a3fed9a1c 100644
--- a/src/hwrenderer/scene/hw_drawstructs.h
+++ b/src/hwrenderer/scene/hw_drawstructs.h
@@ -300,6 +300,7 @@ public:
 
 	FColormap Colormap;	// light and fog
 	PalEntry FlatColor;
+	PalEntry AddColor;
 	ERenderStyle renderstyle;
 
 	float alpha;
diff --git a/src/hwrenderer/scene/hw_flats.cpp b/src/hwrenderer/scene/hw_flats.cpp
index b63987fd0..b609847fd 100644
--- a/src/hwrenderer/scene/hw_flats.cpp
+++ b/src/hwrenderer/scene/hw_flats.cpp
@@ -307,6 +307,7 @@ void GLFlat::DrawFlat(HWDrawInfo *di, FRenderState &state, bool translucent)
 	state.SetColor(lightlevel, rel, di->isFullbrightScene(), Colormap, alpha);
 	state.SetFog(lightlevel, rel, di->isFullbrightScene(), &Colormap, false);
 	state.SetObjectColor(FlatColor | 0xff000000);
+	state.SetAddColor(AddColor | 0xff000000);
 
 	if (hacktype & SSRF_PLANEHACK)
 	{
@@ -357,6 +358,7 @@ void GLFlat::DrawFlat(HWDrawInfo *di, FRenderState &state, bool translucent)
 		state.SetRenderStyle(DefaultRenderStyle());
 		state.SetObjectColor(0xffffffff);
 	}
+	state.SetAddColor(0);
 }
 
 //==========================================================================
@@ -441,16 +443,18 @@ void GLFlat::SetFrom3DFloor(F3DFloor *rover, bool top, bool underside)
 	// FF_FOG requires an inverted logic where to get the light from
 	lightlist_t *light = P_GetPlaneLight(sector, plane.plane, underside);
 	lightlevel = hw_ClampLight(*light->p_lightlevel);
-	
+
 	if (rover->flags & FF_FOG)
 	{
 		Colormap.LightColor = light->extra_colormap.FadeColor;
 		FlatColor = 0xffffffff;
+		AddColor = 0;
 	}
 	else
 	{
 		Colormap.CopyFrom3DLight(light);
 		FlatColor = *plane.flatcolor;
+		// AddColor = sector->SpecialColors[sector_t::add];
 	}
 
 
@@ -505,6 +509,7 @@ void GLFlat::ProcessSector(HWDrawInfo *di, sector_t * frontsector, int which)
 		lightlevel = hw_ClampLight(frontsector->GetFloorLight());
 		Colormap = frontsector->Colormap;
 		FlatColor = frontsector->SpecialColors[sector_t::floor];
+		AddColor = frontsector->SpecialColors[sector_t::add];
 		port = frontsector->ValidatePortal(sector_t::floor);
 		if ((stack = (port != NULL)))
 		{
@@ -560,6 +565,7 @@ void GLFlat::ProcessSector(HWDrawInfo *di, sector_t * frontsector, int which)
 		lightlevel = hw_ClampLight(frontsector->GetCeilingLight());
 		Colormap = frontsector->Colormap;
 		FlatColor = frontsector->SpecialColors[sector_t::ceiling];
+		AddColor = frontsector->SpecialColors[sector_t::add];
 		port = frontsector->ValidatePortal(sector_t::ceiling);
 		if ((stack = (port != NULL)))
 		{
diff --git a/src/hwrenderer/scene/hw_renderstate.h b/src/hwrenderer/scene/hw_renderstate.h
index 3ddb80270..297435422 100644
--- a/src/hwrenderer/scene/hw_renderstate.h
+++ b/src/hwrenderer/scene/hw_renderstate.h
@@ -144,11 +144,12 @@ protected:
 	float mInterpolationFactor;
 
 	FStateVec4 mNormal;
-	FStateVec4 mColor, mColorAdd;
+	FStateVec4 mColor;
 	FStateVec4 mGlowTop, mGlowBottom;
 	FStateVec4 mGlowTopPlane, mGlowBottomPlane;
 	FStateVec4 mGradientTopPlane, mGradientBottomPlane;
 	FStateVec4 mSplitTopPlane, mSplitBottomPlane;
+	PalEntry mAddColor;
 	PalEntry mFogColor;
 	PalEntry mObjectColor;
 	PalEntry mObjectColor2;
@@ -181,6 +182,7 @@ public:
 		mModelMatrixEnabled = false;
 		mTextureMatrixEnabled = false;
 		mSplitEnabled = false;
+		mAddColor = 0;
 		mObjectColor = 0xffffffff;
 		mObjectColor2 = 0;
 		mSoftLight = 0;
@@ -369,6 +371,11 @@ public:
 		mObjectColor2 = pe;
 	}
 
+	void SetAddColor(PalEntry pe)
+	{
+		mAddColor = pe;
+	}
+
 	void SetFog(PalEntry c, float d)
 	{
 		const float LOG2E = 1.442692f;	// = 1/log(2)
diff --git a/src/hwrenderer/utility/hw_draw2d.cpp b/src/hwrenderer/utility/hw_draw2d.cpp
index 0e224b26d..9356c5515 100644
--- a/src/hwrenderer/utility/hw_draw2d.cpp
+++ b/src/hwrenderer/utility/hw_draw2d.cpp
@@ -203,6 +203,7 @@ void Draw2D(F2DDrawer *drawer, FRenderState &state)
 		}
 		state.SetObjectColor(0xffffffff);
 		state.SetObjectColor2(0);
+		state.SetAddColor(0);
 		state.EnableTextureMatrix(false);
 		state.SetEffect(EFF_NONE);
 
diff --git a/src/p_saveg.cpp b/src/p_saveg.cpp
index adfbdfda6..2d83a1545 100644
--- a/src/p_saveg.cpp
+++ b/src/p_saveg.cpp
@@ -293,7 +293,7 @@ FSerializer &Serialize(FSerializer &arc, const char *key, sector_t &p, sector_t
 			("linked_floor", p.e->Linked.Floor.Sectors)
 			("linked_ceiling", p.e->Linked.Ceiling.Sectors)
 			("colormap", p.Colormap, def->Colormap)
-			.Array("specialcolors", p.SpecialColors, def->SpecialColors, 5, true)
+			.Array("specialcolors", p.SpecialColors, def->SpecialColors, 6, true)
 			("gravity", p.gravity, def->gravity)
 			.Terrain("floorterrain", p.terrainnum[0], &def->terrainnum[0])
 			.Terrain("ceilingterrain", p.terrainnum[1], &def->terrainnum[1])
diff --git a/wadsrc/static/shaders/glsl/main.fp b/wadsrc/static/shaders/glsl/main.fp
index c138eb4f1..694d01f29 100644
--- a/wadsrc/static/shaders/glsl/main.fp
+++ b/wadsrc/static/shaders/glsl/main.fp
@@ -114,6 +114,8 @@ vec4 getTexel(vec2 st)
 	if (uObjectColor2.a == 0.0) texel *= uObjectColor;
 	else texel *= mix(uObjectColor, uObjectColor2, gradientdist.z);
 
+	texel += uAddColor;
+
 	return desaturate(texel);
 }
 
diff --git a/wadsrc/static/zscript/mapdata.txt b/wadsrc/static/zscript/mapdata.txt
index 601031f22..5ae796b04 100644
--- a/wadsrc/static/zscript/mapdata.txt
+++ b/wadsrc/static/zscript/mapdata.txt
@@ -235,7 +235,7 @@ struct Sector native play
 {
 
 	native readonly FColormap 	ColorMap;
-	native readonly Color		SpecialColors[5];
+	native readonly Color		SpecialColors[6];
 
 	native Actor 		SoundTarget;