diff --git a/engine/client/render.h b/engine/client/render.h
index e330de547..ac641d4eb 100644
--- a/engine/client/render.h
+++ b/engine/client/render.h
@@ -611,6 +611,7 @@ extern	cvar_t	r_waterwarp;
 extern	cvar_t	r_fullbright;
 extern	cvar_t	r_lightmap;
 extern	cvar_t	r_glsl_offsetmapping;
+extern	cvar_t	r_skyfog;	//additional fog alpha on sky
 extern	cvar_t	r_shadow_playershadows;
 extern	cvar_t	r_shadow_realtime_dlight, r_shadow_realtime_dlight_shadows;
 extern	cvar_t	r_shadow_realtime_dlight_ambient;
diff --git a/engine/client/renderer.c b/engine/client/renderer.c
index b7d3f4a0c..1bf1e6852 100644
--- a/engine/client/renderer.c
+++ b/engine/client/renderer.c
@@ -203,6 +203,7 @@ cvar_t r_wallcolour							= CVARAF ("r_wallcolour", "128 128 128",
 													  "r_wallcolor", CVAR_RENDERERCALLBACK|CVAR_SHADERSYSTEM);//FIXME: broken
 //cvar_t r_walltexture						= CVARF ("r_walltexture", "",
 //												CVAR_RENDERERCALLBACK|CVAR_SHADERSYSTEM);	//FIXME: broken
+cvar_t r_skyfog								= CVARD  ("r_skyfog", "0.5", "This controls an alpha-blend value for fog on skyboxes, cumulative with regular fog alpha.");
 cvar_t r_wateralpha							= CVARF  ("r_wateralpha", "1",
 												CVAR_ARCHIVE | CVAR_SHADERSYSTEM);
 cvar_t r_lavaalpha							= CVARF  ("r_lavaalpha", "",
@@ -842,6 +843,7 @@ void Renderer_Init(void)
 	Cvar_Register (&r_mirroralpha, GLRENDEREROPTIONS);
 	Cvar_Register (&r_softwarebanding_cvar, GRAPHICALNICETIES);
 
+	Cvar_Register (&r_skyfog, GRAPHICALNICETIES);
 	Cvar_Register (&r_skyboxname, GRAPHICALNICETIES);
 	Cmd_AddCommand("sky", R_ForceSky_f);	//QS compat
 	Cmd_AddCommand("loadsky", R_ForceSky_f);//DP compat
diff --git a/engine/client/wad.c b/engine/client/wad.c
index d9d695ee4..16eb60c7a 100644
--- a/engine/client/wad.c
+++ b/engine/client/wad.c
@@ -838,6 +838,8 @@ void Mod_ParseInfoFromEntityLump(model_t *wmodel)	//actually, this should be in
 			Q_strncatz(wads, token, sizeof(wads));	//cache it for later (so that we don't play with any temp memory yet)
 #endif
 		}
+		else if (!strcmp("skyfog", key)) //override cvars so mappers don't end up hacking cvars and fucking over configs (at least in other engines).
+			Cvar_LockFromServer(&r_skyfog, token);
 		else if (!strcmp("fog", key) || !strcmp("airfog", key))	//q1 extension. FIXME: should be made temporary.
 		{
 			key[0] = 'f';