diff --git a/include/light/light.hh b/include/light/light.hh
index 9a05ccc9..b7897b39 100644
--- a/include/light/light.hh
+++ b/include/light/light.hh
@@ -443,6 +443,7 @@ public:
     setting_bool nolights{this, "nolights", false, &output_group, "ignore light entities (only sunlight/minlight)"};
     setting_int32 facestyles{this, "facestyles", 4, &output_group, "max amount of styles per face; requires BSPX lump if > 4"};
     setting_bool exportobj{this, "exportobj", false, &output_group, "export an .OBJ for inspection"};
+    setting_int32 lmshift{this, "lmshift", 4, &output_group, "force a specified lmshift to be applied to the entire map; this is useful if you want to re-light a map with higher quality BSPX lighting without the sources. Will add the LMSHIFT lump to the BSP."};
 
     inline void CheckNoDebugModeSet()
     {
diff --git a/light/bounce.cc b/light/bounce.cc
index 3bfda5c5..03ae60ca 100644
--- a/light/bounce.cc
+++ b/light/bounce.cc
@@ -169,7 +169,9 @@ static void MakeBounceLightsThread(const settings::worldspawn_keys &cfg, const m
         return;
     }
 
-    const vec_t sample_scalar = 1.f / sqrt(area) / (options.extra.value() * options.extra.value()) * (surf.lightmapscale / 16.0);
+    const vec_t sample_divisor = sqrt(area);
+    const vec_t extra_divisor = (options.extra.value() * options.extra.value());
+    const vec_t lmscale_divisor = (16.0 / surf.lightmapscale);
 
     qplane3d faceplane = winding.plane();
 
@@ -188,7 +190,9 @@ static void MakeBounceLightsThread(const settings::worldspawn_keys &cfg, const m
     qvec3d total = {};
 
     for (auto &styleColor : sum) {
-        styleColor.second *= sample_scalar;
+        styleColor.second /= sample_divisor;
+        styleColor.second /= extra_divisor;
+        styleColor.second /= lmscale_divisor;
         styleColor.second *= cfg.bouncescale.value();
         total += styleColor.second;
     }
diff --git a/light/light.cc b/light/light.cc
index 588d01ac..2bbbbcf7 100644
--- a/light/light.cc
+++ b/light/light.cc
@@ -527,6 +527,17 @@ static void LightWorld(bspdata_t *bspdata, bool forcedscale)
 
     if (forcedscale) {
         bspdata->bspx.entries.erase("LMSHIFT");
+    } else if (options.lmshift.isChanged()) {
+        // if we forcefully specified an lmshift lump, we have to generate one.
+        bspdata->bspx.entries.erase("LMSHIFT");
+
+        std::vector<uint8_t> shifts(bsp.dfaces.size());
+
+        for (auto &shift : shifts) {
+            shift = options.lmshift.value();
+        }
+
+        bspdata->bspx.transfer("LMSHIFT", shifts);
     }
 
     auto lmshift_lump = bspdata->bspx.entries.find("LMSHIFT");