diff --git a/ref/gl/gl_local.h b/ref/gl/gl_local.h
index 311838c0..62dcbe47 100644
--- a/ref/gl/gl_local.h
+++ b/ref/gl/gl_local.h
@@ -767,6 +767,7 @@ extern convar_t	gl_nosort;
 extern convar_t	gl_test;		// cvar to testify new effects
 extern convar_t	gl_msaa;
 extern convar_t	gl_stencilbits;
+extern convar_t	gl_overbright;
 
 extern convar_t	r_lighting_extended;
 extern convar_t	r_lighting_ambient;
diff --git a/ref/gl/gl_opengl.c b/ref/gl/gl_opengl.c
index ae3d87cf..19bfe301 100644
--- a/ref/gl/gl_opengl.c
+++ b/ref/gl/gl_opengl.c
@@ -19,6 +19,7 @@ CVAR_DEFINE_AUTO( gl_nosort, "0", FCVAR_GLCONFIG, "disable sorting of translucen
 CVAR_DEFINE_AUTO( gl_test, "0", 0, "engine developer cvar for quick testing new features" );
 CVAR_DEFINE_AUTO( gl_msaa, "1", FCVAR_GLCONFIG, "enable or disable multisample anti-aliasing" );
 CVAR_DEFINE_AUTO( gl_stencilbits, "8", FCVAR_GLCONFIG|FCVAR_READ_ONLY, "pixelformat stencil bits (0 - auto)" );
+CVAR_DEFINE_AUTO( gl_overbright, "1", FCVAR_GLCONFIG, "overbrights" );
 CVAR_DEFINE_AUTO( r_lighting_extended, "1", FCVAR_GLCONFIG, "allow to get lighting from world and bmodels" );
 CVAR_DEFINE_AUTO( r_lighting_ambient, "0.3", FCVAR_GLCONFIG, "map ambient lighting scale" );
 CVAR_DEFINE_AUTO( r_detailtextures, "1", FCVAR_ARCHIVE, "enable detail textures support" );
@@ -1203,6 +1204,7 @@ void GL_InitCommands( void )
 	gEngfuncs.Cvar_RegisterVariable( &gl_msaa );
 	gEngfuncs.Cvar_RegisterVariable( &gl_stencilbits );
 	gEngfuncs.Cvar_RegisterVariable( &gl_round_down );
+	gEngfuncs.Cvar_RegisterVariable( &gl_overbright );
 
 	// these cvar not used by engine but some mods requires this
 	gEngfuncs.Cvar_RegisterVariable( &gl_polyoffset );
diff --git a/ref/gl/gl_rmain.c b/ref/gl/gl_rmain.c
index 2a35a94f..cf4c7594 100644
--- a/ref/gl/gl_rmain.c
+++ b/ref/gl/gl_rmain.c
@@ -1001,6 +1001,15 @@ void R_GammaChanged( qboolean do_reset_gamma )
 	}
 }
 
+static void R_CheckGamma( void )
+{
+	if( FBitSet( gl_overbright.flags, FCVAR_CHANGED ))
+	{
+		R_GammaChanged( false );
+		ClearBits( gl_overbright.flags, FCVAR_CHANGED );
+	}
+}
+
 /*
 ===============
 R_BeginFrame
@@ -1016,6 +1025,8 @@ void R_BeginFrame( qboolean clearScene )
 		pglClear( GL_COLOR_BUFFER_BIT );
 	}
 
+	R_CheckGamma();
+
 	R_Set2DMode( true );
 
 	// draw buffer stuff
diff --git a/ref/gl/gl_rsurf.c b/ref/gl/gl_rsurf.c
index 04fb0245..9e5cea52 100644
--- a/ref/gl/gl_rsurf.c
+++ b/ref/gl/gl_rsurf.c
@@ -600,9 +600,9 @@ void R_AddDynamicLights( msurface_t *surf )
 
 				if( dist < minlight )
 				{
-					bl[0] += ((int)((rad - dist) * 256) * gEngfuncs.LightToTexGamma( dl->color.r )) / 256;
-					bl[1] += ((int)((rad - dist) * 256) * gEngfuncs.LightToTexGamma( dl->color.g )) / 256;
-					bl[2] += ((int)((rad - dist) * 256) * gEngfuncs.LightToTexGamma( dl->color.b )) / 256;
+					bl[0] += ((int)((rad - dist) * 256) * dl->color.r ) / 256;
+					bl[1] += ((int)((rad - dist) * 256) * dl->color.g ) / 256;
+					bl[2] += ((int)((rad - dist) * 256) * dl->color.b ) / 256;
 				}
 			}
 		}
@@ -742,11 +742,15 @@ static void R_BuildLightMap( msurface_t *surf, byte *dest, int stride, qboolean
 	int		sample_size;
 	mextrasurf_t	*info = surf->info;
 	color24		*lm;
+	int lightscale;
 
 	sample_size = gEngfuncs.Mod_SampleSizeForFace( surf );
 	smax = ( info->lightextents[0] / sample_size ) + 1;
 	tmax = ( info->lightextents[1] / sample_size ) + 1;
 	size = smax * tmax;
+	if( gl_overbright.value )
+		lightscale = 256;
+	else lightscale = ( pow( 2.0f, 1.0f / v_lightgamma->value ) * 256 ) + 0.5;
 
 	lm = surf->samples;
 
@@ -759,9 +763,9 @@ static void R_BuildLightMap( msurface_t *surf, byte *dest, int stride, qboolean
 
 		for( i = 0, bl = r_blocklights; i < size; i++, bl += 3, lm++ )
 		{
-			bl[0] += gEngfuncs.LightToTexGamma( lm->r ) * scale;
-			bl[1] += gEngfuncs.LightToTexGamma( lm->g ) * scale;
-			bl[2] += gEngfuncs.LightToTexGamma( lm->b ) * scale;
+			bl[0] += lm->r * scale;
+			bl[1] += lm->g * scale;
+			bl[2] += lm->b * scale;
 		}
 	}
 
@@ -777,9 +781,16 @@ static void R_BuildLightMap( msurface_t *surf, byte *dest, int stride, qboolean
 	{
 		for( s = 0; s < smax; s++ )
 		{
-			dest[0] = Q_min((bl[0] >> 7), 255 );
-			dest[1] = Q_min((bl[1] >> 7), 255 );
-			dest[2] = Q_min((bl[2] >> 7), 255 );
+			int i;
+			for( i = 0; i < 3; i++ )
+			{
+				int t = bl[i] * lightscale >> 14;
+
+				if( t > 1023 )
+					t = 1023;
+
+				dest[i] = gEngfuncs.LightToTexGammaEx( t ) >> 2;
+			}
 			dest[3] = 255;
 
 			bl += 3;
@@ -944,7 +955,15 @@ void R_BlendLightmaps( void )
 	pglDepthFunc( GL_EQUAL );
 
 	pglDisable( GL_ALPHA_TEST );
-	pglBlendFunc( GL_ZERO, GL_SRC_COLOR );
+	if( gl_overbright.value )
+	{
+		pglBlendFunc( GL_DST_COLOR, GL_SRC_COLOR );
+		pglColor4f( 128.0f / 192.0f, 128.0f / 192.0f, 128.0f / 192.0f, 1.0f );
+	}
+	else
+	{
+		pglBlendFunc( GL_ZERO, GL_SRC_COLOR );
+	}
 	pglTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 
 	// render static lightmaps first