diff --git a/src/engine/renderer/tr_bsp.cpp b/src/engine/renderer/tr_bsp.cpp
index a5bfab45ee..bc7a21ae00 100644
--- a/src/engine/renderer/tr_bsp.cpp
+++ b/src/engine/renderer/tr_bsp.cpp
@@ -4106,12 +4106,6 @@ void R_LoadLightGrid( lump_t *l )
 		tmpDirected[ 2 ] = in->directed[ 2 ];
 		tmpDirected[ 3 ] = 255;
 
-		if ( tmpAmbient[0] < r_forceAmbient.Get() &&
-			tmpAmbient[1] < r_forceAmbient.Get() &&
-			tmpAmbient[2] < r_forceAmbient.Get() ) {
-			VectorSet( tmpAmbient, r_forceAmbient.Get(), r_forceAmbient.Get(), r_forceAmbient.Get() );
-		}
-
 		if ( tr.legacyOverBrightClamping )
 		{
 			R_ColorShiftLightingBytes( tmpAmbient );
@@ -4124,6 +4118,18 @@ void R_LoadLightGrid( lump_t *l )
 			directedColor[ j ] = tmpDirected[ j ] * ( 1.0f / 255.0f );
 		}
 
+		const float forceAmbient = r_forceAmbient.Get();
+		if ( ambientColor[0] < forceAmbient &&
+			ambientColor[1] < forceAmbient &&
+			ambientColor[2] < forceAmbient &&
+			/* Make sure we don't change the (0, 0, 0) points because those are points in walls,
+			which we'll fill up by interpolating nearby points later */
+			( ambientColor[0] != 0 ||
+			ambientColor[1] != 0 || 
+			ambientColor[2] != 0 ) ) {
+			VectorSet( ambientColor, forceAmbient, forceAmbient, forceAmbient );
+		}
+
 		// standard spherical coordinates to cartesian coordinates conversion
 
 		// decode X as cos( lat ) * sin( long )
@@ -4332,9 +4338,9 @@ void R_LoadEntities( lump_t *l, std::string &externalEntities )
 		}
 
 		// check for ambient color
-		else if ( !Q_stricmp( keyname, "_color" ) || !Q_stricmp( keyname, "ambientColor" ) )
+		else if ( !Q_stricmp( keyname, "ambientColor" ) )
 		{
-			if ( r_forceAmbient.Get() == 0 ) {
+			if ( r_forceAmbient.Get() == -1 ) {
 				sscanf( value, "%f %f %f", &tr.ambientLight[0], &tr.ambientLight[1],
 					&tr.ambientLight[2] );
 
diff --git a/src/engine/renderer/tr_init.cpp b/src/engine/renderer/tr_init.cpp
index bcd1dc30db..7156dcf52d 100644
--- a/src/engine/renderer/tr_init.cpp
+++ b/src/engine/renderer/tr_init.cpp
@@ -242,8 +242,8 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 	cvar_t      *r_wolfFog;
 	cvar_t      *r_noFog;
 
-	Cvar::Range<Cvar::Cvar<float>> r_forceAmbient( "r_forceAmbient", "Minimal light amount in lightGrid", Cvar::NONE,
-		0.125f, 0.0f, 0.3f );
+	Cvar::Range<Cvar::Cvar<float>> r_forceAmbient( "r_forceAmbient", "Minimal light amount in lightGrid; -1 to use map value",
+		Cvar::CHEAT, -1.0f, -1.0f, 0.3f );
 	Cvar::Cvar<float> r_ambientScale( "r_ambientScale", "Scale lightGrid produced by ambientColor keyword by this much", Cvar::CHEAT, 1.0 );
 	cvar_t      *r_lightScale;
 	cvar_t      *r_debugSort;